Site Sponsors
Page 2 of 2 FirstFirst 1 2
Results 51 to 76 of 76

Thread: IQ4150 Frame Averaging Comparisons

  1. #51
    Workshop Member
    Join Date
    May 2008
    Location
    NYC
    Posts
    3,912
    Post Thanks / Like
    Images
    7

    Re: IQ4150 Frame Averaging Comparisons

    Quote Originally Posted by vjbelle View Post
    I agree that the Frame Sampling images look slightly softer than a long exposure of the same scene. I also agree that it is the lack of 'any' noise that fools my eyes a little.

    I also wanted to know how a Frame Sampling image would cope with some slight camera movement. I took a long exposure of 40 seconds and a frame sampling image (2.0s, 40 seconds, 20 images) of the same scene. The frame sampling image was continuous.

    I was fairly certain that slight camera movement would have no effect on the long exposure and I was right. But the results for the frame sampling image were also the same. If there is any difference it is so subtle that I can't detect it.

    What this means to me is that for a static scene I could possibly have a little wind vibration without loss of image quality.

    By movement I mean that half way through each test I physically tapped the side of camera a couple of time - I could see the camera move. I find this very encouraging.

    Victor
    Camera shake would have identical impact as on a long exposure, with one exception...

    Imagine you're doing a single long exposure (e.g. 90 seconds) from a tripod near a road and 45 seconds into that exposure you notice a truck coming your way (that will cause light and vibration), if you choose to end the exposure at that point the image will be one stop under exposed.

    Using frame averaging in the same scenario, ending the sequence early will NOT effect the histogram/exposure of the scene. It will simply average fewer frames.

    Even if you only notice the vibration and stop it AFTER it has begun you might well get away with it if there are no specular highlights (e.g. street lamps). For example if you are 6 minutes into a frame averaging exposure, bump the tripod, and push the cancel/stop button within two seconds of that bump, you'll have only 2 seconds of "bad" image content blended with 360 seconds of "good" image content, so you shouldn't see much, if any ghosting or loss of sharpness, and again, with frame averaging the final exposure will be correct (and more robust to post processing than a single long capture) no matter what the originally intended exposure length was and how prematurely you ended it. Of course if you were going for a motion smoothing effect (e.g. turning a waterfall into silk) that requires X minutes and you stop the averaging early you won't get quite the intended motion smoothing, but in many cases the difference could be minor (e.g. stopping 2 minutes into a 3 minute frame averaging won't effect the look of motion smoothing that much).

    We mention this in my colleague Arnab's frame averaging write up.
    Doug Peterson , Digital Transitions | Email
    Dealer for: Phase One, Mamiya Leaf, Arca-Swiss, Cambo, Eizo, Profoto
    Office: 877.367.8537. Cell: 740.707.2183
    Likes 1 Member(s) liked this post

  2. #52
    Senior Subscriber Member
    Join Date
    Sep 2011
    Location
    Englewood, CO
    Posts
    2,627
    Post Thanks / Like
    Images
    1254

    Re: IQ4150 Frame Averaging Comparisons

    Quote Originally Posted by Craig Stocks View Post
    The two seem fundamentally the same with some differences in implementation. Both seem to create an image that is the average of numerous frames calculated directly from sensor data. It's useful for either simulating an ND filter or to reduce noise in shadows.

    The Sony Smooth Reflection (SR) app produces both a RAW and JPEG result.

    The SR interface provides some settings for specific scenarios as well as a custom setting where you can choose the number of frames, but the choices are in rather large increments.

    SR doesn't use an electronic shutter so can't do gapless captures.

    SR doesn't seem to have a shutter speed limitation other than the 30 second limit of the Sony camera.

    The SR app costs $4.99 whereas Phase One's Frame Averaging tool is free (well, free with the purchase of a $50,000 camera).

    Note that the Play Memories apps (like Smooth Reflections) are not supported by newer Sony A7 and A9 cameras. It is still supported on the a6xxx series cameras.

    I toyed with it on my Sony cameras a few years ago and promptly forgot all about it. The current discussion has reminded it's available and I envision using it more frequently now. I have it installed on both my A7R2 and an older a6000. In round numbers the A7R2 approaches IQ4150 noise levels with double the frames. The a6000 improves dramatically with averaging but never get very close.
    Thank you very much Craig! I really appreciate your explanation.

    I understand much more after I studied about the SR as there are a lot of information and examples on the web.

    I wonder why Sony dropped the SR and other Playmemories camera applications for the A7R III. In-camera processing seems to be very convenient.

    Yeah! You're right Craig! Phase One's FA is a bargain compared to Sony ($4.99). Very well thought


    Best

    Pramote
    Likes 1 Member(s) liked this post

  3. #53
    Super Duper
    Senior Member

    Join Date
    May 2012
    Posts
    2,826
    Post Thanks / Like
    Images
    3

    Re: IQ4150 Frame Averaging Comparisons

    Quote Originally Posted by vjbelle View Post
    I agree that the Frame Sampling images look slightly softer than a long exposure of the same scene. I also agree that it is the lack of 'any' noise that fools my eyes a little. Victor
    Victor

    I guess my quetion is in fact ARE the FA images softer?
    Thanks 1 Member(s) thanked for this post

  4. #54
    Member
    Join Date
    Aug 2011
    Location
    Illinois, USA
    Posts
    239
    Post Thanks / Like

    Re: IQ4150 Frame Averaging Comparisons

    One point to address some misinformation I've seen on frame averaging - it is NOT the appropriate tool for star trails. Stacking star trails and stacking images for noise reduction are two very different processes and yield different results. Both involve "stacking" but the methods of combining individual frames are different.

    For star trails: Shoot continuous frames with the camera stationary on a tripod. Load the frames into Photoshop as layers and set the blending mode to Lighten. The foreground remains aligned and the stars "paint" their way across the sky.

    For noise reduction (frame averaging): Shoot continuous frames with the camera stationary or on a tracking mount. Load the frames into Photoshop as layers and align the layers so that the stars are aligned. (If foreground is visible it will no longer be aligned and will appear blurry when the frames are averaged.) Convert the layers to a smart object and set the stacking mode to Mean. This procedure yields a result identical to in-camera frame averaging.

    The key difference is the method of combining the frames or layers. Averaging takes the average color and brightness of each pixel, Lighten blend mode uses the brightest value for each pixel. Though they can be similar, one long exposure is not the same as many short exposures, especially when there are moving specular highlights like stars or car lights.

    Stacking in Lighten blend mode (such as for start trails) does provide some noise reduction but not as much as averaging. It also makes single pixel noise worse since it combines all of the single pixel noise into the final image rather than averaging it out.

    I haven't experimented (yet) but I suspect that light trails from cars will behave like star trails and require either a true long exposure or stacking in Photoshop in Lighten blend mode.

    These two examples show the same 30 frames stacked in Lighten blending mode (clear star trails) and averaged (nearly invisible star trails).
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	DSC01796 copy.jpg 
Views:	11 
Size:	561.1 KB 
ID:	143206   Click image for larger version. 

Name:	DSC01772-Edit.jpg 
Views:	10 
Size:	625.3 KB 
ID:	143207  
    Thanks 1 Member(s) thanked for this post

  5. #55
    Workshop Member
    Join Date
    May 2008
    Location
    NYC
    Posts
    3,912
    Post Thanks / Like
    Images
    7

    Re: IQ4150 Frame Averaging Comparisons

    Quote Originally Posted by Craig Stocks View Post
    One point to address some misinformation I've seen on frame averaging - it is NOT the appropriate tool for star trails. Stacking star trails and stacking images for noise reduction are two very different processes and yield different results. Both involve "stacking" but the methods of combining individual frames are different.

    For star trails: Shoot continuous frames with the camera stationary on a tripod. Load the frames into Photoshop as layers and set the blending mode to Lighten. The foreground remains aligned and the stars "paint" their way across the sky.

    For noise reduction (frame averaging): Shoot continuous frames with the camera stationary or on a tracking mount. Load the frames into Photoshop as layers and align the layers so that the stars are aligned. (If foreground is visible it will no longer be aligned and will appear blurry when the frames are averaged.) Convert the layers to a smart object and set the stacking mode to Mean. This procedure yields a result identical to in-camera frame averaging.

    The key difference is the method of combining the frames or layers. Averaging takes the average color and brightness of each pixel, Lighten blend mode uses the brightest value for each pixel. Though they can be similar, one long exposure is not the same as many short exposures, especially when there are moving specular highlights like stars or car lights.

    Stacking in Lighten blend mode (such as for start trails) does provide some noise reduction but not as much as averaging. It also makes single pixel noise worse since it combines all of the single pixel noise into the final image rather than averaging it out.
    I guess it's somewhat a semantic-definition thing, but I'd consider Max-hold ("Lighten" in Photoshop terms) to still be frame-averaging (frame "stacking" is probably more accurate but too generic IMO). It's just frame averaging with Max rather than Mean.

    Mean basically acts exactly as a single long exposure would. Max is decidedly different than any single capture method. As is Median or Mode which would allow for removal of crowds from street scenes and other interesting visual effects.

    My senior thesis was on star trails. In Winter. In Ohio. BRRRRRRR.

    I'd LOVE to see Max and Median/Mode frame averaging added to the IQ4's frame averaging tool.


    Quote Originally Posted by Craig Stocks View Post
    I haven't experimented (yet) but I suspect that light trails from cars will behave like star trails and require either a true long exposure or stacking in Photoshop in Lighten blend mode.
    Most car light trail imagery I've seen or done has been with a single long exposure, so would be well served by P1's current implementation of frame averaging.

    Edit: Of course, Phase One is the first company I'm aware of to offer totally gapless frame averaging, so maybe that's why I haven't previously seen frame-averaging car light trail imagery.
    Last edited by dougpeterson; 30th July 2019 at 09:05.
    Doug Peterson , Digital Transitions | Email
    Dealer for: Phase One, Mamiya Leaf, Arca-Swiss, Cambo, Eizo, Profoto
    Office: 877.367.8537. Cell: 740.707.2183

  6. #56
    Member
    Join Date
    Aug 2011
    Location
    Illinois, USA
    Posts
    239
    Post Thanks / Like

    Re: IQ4150 Frame Averaging Comparisons

    Quote Originally Posted by dougpeterson View Post

    Mean basically acts exactly as a single long exposure would. Max is decidedly different than any single capture method. As is Median or Mode which would allow for removal of crowds from street scenes and other interesting visual effects.\
    I respectfully disagree, particularly when moving highlights like stars or car lights are involved. Consider the example of a single 30 second exposure of a dark scene where during that time a strobe fully illuminates a subject in the scene. That subject will be fully exposed at the end of the strobe flash and will still be rendered as fully exposed at the end of 30 seconds. Now consider a frame average of 30 1-second exposures where that same strobe illuminates the same subject during one of those frames. In that case the fully illuminated pixels will be averaged with 29 other samples of dark pixels. The result will be that the subject will not be rendered as fully illuminated, it will be 1/30th illuminated and 29/30ths dark. A single exposure is the summation of all illumination during the exposure which is different from the average of multiple samples taken during the same period.

    I believe my test illustrates the difference for star trails.

    Quote Originally Posted by dougpeterson View Post
    I'd LOVE to see Max and Median/Mode frame averaging added to the IQ4's frame averaging tool.
    I agree, and we might as well throw in Minimum and other methods too. Maximum would be useful for lightpainting, star trails and automotive streaks. Mode is really useful best for removing moving elements in a scene, such as people or cars. It terms of programming though Mode is probably much more memory intensive since you can't (as far as I know) calculate a rolling mode in the same way you can calculate a rolling mean, minimum or maximum.

  7. #57
    Senior Member
    Join Date
    Dec 2007
    Location
    Little Rock AR
    Posts
    2,349
    Post Thanks / Like
    Images
    8

    Re: IQ4150 Frame Averaging Comparisons

    We are getting way off course here, but I would state that with Star trails, I find the best solution is running a Max, then Mean on same Smart object, then layer the two back together. Max will pull much more noise, Mean almost none, and a layered blend seems to get the best results for me. Working with a partial moon 1/2 to 3/4 will give the photographer almost daylight looking foreground areas, which I greatly prefer over dark, or pushed ISO, noise etc. Most non educated photographers just feel it’s faked, but sadly it’s actually not, but instead a ton of work. Not to say there is only one way to do this, as there are many, this just works the best for me.

    You will always have gaps, even in a single long exposure. They are very faint with a single long exposure but still there, where as with a long series of 1.5 minute exposures, you will have slight gap at where each frame end. Most obviously the camera cannot be moved at all, or the trails will align with a drop, or jerk where the camera move happened, even hitting the playback button can be enough to screw up a long 1.5 hour series.

    The only way I know to smooth them out is the additional step of running Startracer, which moves the image to catch the gaps and of course blurs any landscape portion, which has to be blended back. Startracer works with any wide angle lens, but is harder to get a solution on the MF wides.

    Paul C

  8. #58
    Member
    Join Date
    Aug 2011
    Location
    Illinois, USA
    Posts
    239
    Post Thanks / Like

    Re: IQ4150 Frame Averaging Comparisons

    This pair of samples compares one 8-second exposure where I walked through the scene holding a flashlight (pointed at the camera) and a frame average of 8 1-second exposures with ISO adjusted to achieve the same overall exposure (ISO 50 and ISO 400).

    There are two things of note:

    1 - in the single frame the light streak is full exposed at 100% luminosity (RGB 255,255,255) and is completely opaque. In the stacked frame the light streak is not fully exposed (around 85% luminosity) and you can see some detail behind the light. That's due to the averaging nature of having one frame with the light and 7 frames without the light.

    2 - Notice that in the averaged version the light streak is pink/magenta rather than white or gray. I've been working with my dealer to create a support case for what appears to be a problem in the calculations. Anytime a bright highlight is only present in a very small percentage of the frames it's rendered pink/magenta rather than gray. A similar stack in Photoshop would render it as gray. My guess is that it has to do with how the two green channels are handled in the calculation. It doesn't seem to matter if the highlight is from an LED, tungsten or flash source. The problem is very repeatable on my back.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	IQ4 150MP-19-07-30-P0005267--C1-11.jpg 
Views:	9 
Size:	373.3 KB 
ID:	143208   Click image for larger version. 

Name:	IQ4 150MP-19-07-30-P0005269-8.000s, Automated Frame Average-C1-11.jpg 
Views:	6 
Size:	890.0 KB 
ID:	143209  

  9. #59
    Senior Member
    Join Date
    Dec 2007
    Location
    Little Rock AR
    Posts
    2,349
    Post Thanks / Like
    Images
    8

    Re: IQ4150 Frame Averaging Comparisons

    Craig.

    Good catch. Wayne Fox noticed this effect in some shots he took at the ocean. Same type of thing. Small areas of bright light on the water.

    Makes me wonder how this will work on a steam flowing in sunlight.

    Paul C

  10. #60
    Member
    Join Date
    Aug 2011
    Location
    Illinois, USA
    Posts
    239
    Post Thanks / Like

    Re: IQ4150 Frame Averaging Comparisons

    Quote Originally Posted by Paul2660 View Post
    The only way I know to smooth them out is the additional step of running Startracer, which moves the image to catch the gaps and of course blurs any landscape portion, which has to be blended back. Startracer works with any wide angle lens, but is harder to get a solution on the MF wides.

    Paul C
    I've had good luck simply stacking with Lighten blend mode and haven't noticed gaps when using the IQ3100, but maybe I've just been lucky. I use the time lapse tool with zero gap and enable the electronic shutter. StarStax has a method to fill in gaps in star trails and it seems to work pretty well but it can't work with P1 RAW files so you need to create a set of JPEGs or TIFFs first. I've used it with some Sony files that are more prone to showing gaps.
    Thanks 1 Member(s) thanked for this post

  11. #61
    Workshop Member
    Join Date
    May 2008
    Location
    NYC
    Posts
    3,912
    Post Thanks / Like
    Images
    7

    Re: IQ4150 Frame Averaging Comparisons

    Quote Originally Posted by Craig Stocks View Post
    This pair of samples compares one 8-second exposure where I walked through the scene holding a flashlight (pointed at the camera) and a frame average of 8 1-second exposures with ISO adjusted to achieve the same overall exposure (ISO 50 and ISO 400).

    There are two things of note:

    1 - in the single frame the light streak is full exposed at 100% luminosity (RGB 255,255,255) and is completely opaque. In the stacked frame the light streak is not fully exposed (around 85% luminosity) and you can see some detail behind the light. That's due to the averaging nature of having one frame with the light and 7 frames without the light.

    2 - Notice that in the averaged version the light streak is pink/magenta rather than white or gray. I've been working with my dealer to create a support case for what appears to be a problem in the calculations. Anytime a bright highlight is only present in a very small percentage of the frames it's rendered pink/magenta rather than gray. A similar stack in Photoshop would render it as gray. My guess is that it has to do with how the two green channels are handled in the calculation. It doesn't seem to matter if the highlight is from an LED, tungsten or flash source. The problem is very repeatable on my back.
    I think (2) is magenta in the highlights because it's blown out in some of the frames that are being averaged. It's important not to blow out pixels in a frame-averaged image. The pixels near the blow out can show purple fringing which will then average in. The same thing can happen on seculars when shooting seascapes for example.

    I'd suggest using the Raw File Clipping Warning in live view to avoid this.
    Doug Peterson , Digital Transitions | Email
    Dealer for: Phase One, Mamiya Leaf, Arca-Swiss, Cambo, Eizo, Profoto
    Office: 877.367.8537. Cell: 740.707.2183

  12. #62
    Member
    Join Date
    Feb 2017
    Posts
    101
    Post Thanks / Like

    Re: IQ4150 Frame Averaging Comparisons

    Quote Originally Posted by Craig Stocks View Post
    ...Notice that in the averaged version the light streak is pink/magenta rather than white or gray.
    That's because the averaging is being done prior to white balancing, so RGB = 1,1,1 is not white after WB.

    Jim
    Thanks 1 Member(s) thanked for this post

  13. #63
    Member
    Join Date
    Aug 2011
    Location
    Illinois, USA
    Posts
    239
    Post Thanks / Like

    Re: IQ4150 Frame Averaging Comparisons

    Whatever the mechanism of the error turns out to be Phase One needs to address it. I've submitted RAW files for the support case but I doubt if we'll ever hear the details. FWIW - the Sony frame averaging tool works fine in that regard and does not pick up magenta in highlights, they come out as a nice gray.

  14. #64
    Senior Member
    Join Date
    Jul 2016
    Posts
    353
    Post Thanks / Like

    Re: IQ4150 Frame Averaging Comparisons

    Quote Originally Posted by dougpeterson View Post
    I think (2) is magenta in the highlights because it's blown out in some of the frames that are being averaged. It's important not to blow out pixels in a frame-averaged image. The pixels near the blow out can show purple fringing which will then average in. The same thing can happen on seculars when shooting seascapes for example.

    I'd suggest using the Raw File Clipping Warning in live view to avoid this.
    The explanation is actually very simple for that.

    Waves are things that change colors from extreme to extreme.

    What you are seeing is not an artifact but white breakwater of the wave being averaged with the dark water that is probably present in that part of the picture when the wave is not there.

    It is working as intended, in that situation you would have to simply increase the frame count to account for that.

  15. #65
    Member
    Join Date
    Aug 2011
    Location
    Illinois, USA
    Posts
    239
    Post Thanks / Like

    Re: IQ4150 Frame Averaging Comparisons

    For what it's worth (if anyone's still following this thread)... I did some more test shots with the IQ4 150 to reproduce the magenta cast in intermittent highlights in a frame averaged sequence.

    The short version - The green channels are the first to clip, so I presume averaging clipped green channels with un-clipped red and blue leads to a magenta cast. However, the magenta cast does not show up in a single frame where highlights are clipped in the green channel or in a frame averaged set with constant illumination. Also, given the same test process and in-camera frame averaged RAW output the Sony a7R2 does not show magenta in the highlights.

    The longer version:

    Test setup: Phase One XF with IQ4 150, ISO 50, 1.6 seconds @f/8 with Phase One 120 mm MF macro shooting through an LCC plate. The target was a white board illuminated by and LED source. The result is almost evenly illuminated except for some natural vignetting. I captured a single frame and a FA frame from 10 frames. I also did an FA set where I turned off the LED after the 1st frame.

    All photos were viewed in Capture One with all sliders at their defaults and exported as sRGB JPEGs to share. I also exported DNG versions to analyze with RawDigger, especially single frames so I could understand what and where clipping was occuring.

    Results:

    The center of the single frame shows clipping in the two green channels, no clipping outside of the center.

    The single frame does not show a magenta cast in the center

    A stack of 10 frames with the LED illuminated throughout does not show the magenta cast, in terms of color it looks just like the single frame.

    A stack of 10 where the LED was turned off after the 1st frame shows a strong magenta cast in the central region where the green channels were clipped in the single frame.

    The Sony A7R2 using the same EV (ISO up one stop, shutter speed down one stop) did not clip in the green channels and did not show any magenta cast

    The Sony with exposure increased one EV did clip in the green channels about like the P1 but did not exhibit the magenta cast.

    I still believe it's a problem with the way P1 is doing the averaging, but it's probably the natural outcome of averaging clipped and non-clipped channels. With the greens clipped the red and blue would take over. However, a single frame with similar clipping doesn't result in a magenta cast and Sony's process seems to accommodate the clipping without introducing a color cast.

    Bottom line, very bright transient highlights of any size in a frame averaged set can take on a magenta tint.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	IQ4 150MP-19-08-01-P0005377--C1-11.jpg 
Views:	4 
Size:	50.4 KB 
ID:	143223   Click image for larger version. 

Name:	IQ4 150MP-19-08-01-P0005378-14.400s, Automated Frame Average-C1-11.jpg 
Views:	5 
Size:	96.9 KB 
ID:	143224   Click image for larger version. 

Name:	IQ4150 RAW Histogram.jpg 
Views:	4 
Size:	321.8 KB 
ID:	143225   Click image for larger version. 

Name:	ILCE-7RM2-20190801-DSC02244-C1-11.jpg 
Views:	4 
Size:	37.3 KB 
ID:	143226   Click image for larger version. 

Name:	ILCE-7RM2-20190801-DSC02247-C1-11.jpg 
Views:	6 
Size:	64.4 KB 
ID:	143227  

    Click image for larger version. 

Name:	Sony A7R2 Overexposed Histogram.jpg 
Views:	4 
Size:	301.8 KB 
ID:	143228  
    Thanks 4 Member(s) thanked for this post
    Likes 4 Member(s) liked this post

  16. #66
    Workshop Member
    Join Date
    May 2008
    Location
    NYC
    Posts
    3,912
    Post Thanks / Like
    Images
    7

    Re: IQ4150 Frame Averaging Comparisons

    Craig: that's a great contribution to the community! Thanks for all the work!
    Doug Peterson , Digital Transitions | Email
    Dealer for: Phase One, Mamiya Leaf, Arca-Swiss, Cambo, Eizo, Profoto
    Office: 877.367.8537. Cell: 740.707.2183
    Likes 1 Member(s) liked this post

  17. #67
    Workshop Member Wayne Fox's Avatar
    Join Date
    Nov 2009
    Location
    Draper, Utah
    Posts
    966
    Post Thanks / Like
    Images
    135

    Re: IQ4150 Frame Averaging Comparisons

    Quote Originally Posted by Craig Stocks View Post
    The center of the single frame shows clipping in the two green channels, no clipping outside of the center.
    Did you try the test to avoid any clipping with the IQ4 150?
    wayne
    My gallery

  18. #68
    Senior Member
    Join Date
    Oct 2008
    Location
    Munich
    Posts
    1,071
    Post Thanks / Like
    Images
    1

    Re: IQ4150 Frame Averaging Comparisons

    It should not be necessary. As it should render as grey not pink.

    Quote Originally Posted by Wayne Fox View Post
    Did you try the test to avoid any clipping with the IQ4 150?
    Christopher Hauser
    http://www.chauser.eu

  19. #69
    Member
    Join Date
    Aug 2011
    Location
    Illinois, USA
    Posts
    239
    Post Thanks / Like

    Re: IQ4150 Frame Averaging Comparisons

    Quote Originally Posted by Wayne Fox View Post
    Did you try the test to avoid any clipping with the IQ4 150?
    Yes, I did not see the magenta cast if the green channels were not clipped.
    Likes 2 Member(s) liked this post

  20. #70
    Senior Member etrump's Avatar
    Join Date
    Jan 2009
    Posts
    1,364
    Post Thanks / Like

    Re: IQ4150 Frame Averaging Comparisons

    I’ve noticed it’s better to avoid clipping in all channels with a 1/3 stop under exposure as the shadows remain clean when raising them in post. Clipped channels do not seem to be handled like C1 where the missing detail is estimated from the other two channels.

    Quote Originally Posted by Craig Stocks View Post
    Yes, I did not see the magenta cast if the green channels were not clipped.
    Ed Cooley

    Visit My Website
    Likes 1 Member(s) liked this post

  21. #71
    Workshop Member Wayne Fox's Avatar
    Join Date
    Nov 2009
    Location
    Draper, Utah
    Posts
    966
    Post Thanks / Like
    Images
    135

    Re: IQ4150 Frame Averaging Comparisons

    Quote Originally Posted by Christopher View Post
    It should not be necessary. As it should render as grey not pink.
    the sensor supplies false color data because one channel is clipped, and the camera is supposed to figure out there’s a problem?

    Necessary or not, it seems to resolve the issue, and since frame averaging lowers the noise floor dramatically, dropping exposure slightly shouldn’t be an issue.
    wayne
    My gallery
    Likes 1 Member(s) liked this post

  22. #72
    Senior Member
    Join Date
    Oct 2008
    Location
    Munich
    Posts
    1,071
    Post Thanks / Like
    Images
    1

    Re: IQ4150 Frame Averaging Comparisons

    Well Photoshop does it, Sony does it... so shouldn’t be hard for Phase One... or perhaps it is.

    Besides that. There are always scenes where one cannot get around not blowing something. And it should be possible.

    Quote Originally Posted by Wayne Fox View Post
    the sensor supplies false color data because one channel is clipped, and the camera is supposed to figure out there’s a problem?

    Necessary or not, it seems to resolve the issue, and since frame averaging lowers the noise floor dramatically, dropping exposure slightly shouldn’t be an issue.
    Christopher Hauser
    http://www.chauser.eu

  23. #73
    New Member
    Join Date
    Feb 2019
    Location
    Germany
    Posts
    6
    Post Thanks / Like

    Re: IQ4150 Frame Averaging Comparisons

    Quote Originally Posted by Christopher View Post
    Well Photoshop does it, Sony does it... so shouldn’t be hard for Phase One... or perhaps it is.

    Besides that. There are always scenes where one cannot get around not blowing something. And it should be possible.
    Photoshop is able to do it because the averaging is done on demosaiced and white balanced image data where the raw converter has already recovered some of the lost highlight information by adjusting the other channel and interpolating. The IQ4 Frane Averaging only works with the raw data.

    Based on the strict mean stacking math the magenta cast in Craig's sample images comes from the clipping of the green channel. It's not a bug. In those areas the sensor couldn't capture the additional levels of green coming in on top of the clipped data while the other channels captured their light levels correctly. Since Craig clipped the green channel only in one of the ten averaged frames the averaged green levels in those areas in the final raw file are far from clipped. But as Wayne already mentioned, it's false information. The correct amount of green is missing. And as Jim pointed out, when the camera profile and white balance is applied the false color shows up as magenta (lack of green). Since the raw file isn't clipped Capture One doesn't do any of the highlight color recovery that it can do when a channel of the raw file is clipped. The software can't tell if this is false color or not.
    Ten frames aren't enough to smooth out such a clipping in one of the individual exposures, especially since the other frames got much lower exposure with the LED panel turned off. If the light would not have been turned off but only dimmed a stop or so to bring the green back in range for the rest of the sequence then I'm sure the magenta cast would have been less significant. On Craig's other sample with the light trail trough the frame it's basically the same thing. The local areas where the false color occurs was clipped only for a single frame in the stack of ten while those areas received much less light in the other frames.

    Doug already mentioned that the issue can be avoided by simply underexposing enough to avoid any clipping or by using a lot more frames for the averaging. If these conditions cannot be met then Frame Averaging might not be the right tool. For long night sequences you should be aware of your scene to protect the lens from bright lights crossing the frame that may cause clipping. In the large format days I used to hold the dark slide in front of the lens during long night exposures when I felt the image required protection from temporary bright light sources. With the Frame Averaging tool you can simply stop the sequence earlier and then continue when the light levels are back to where you want them to be. But currently the two second max shutter speed limits the use of this tool for night photography anyway.

    I think the Frame Averaging tool is powerful enough that it deserves a proper description in the manual with warnings about the pitfalls that the user might face. But I'm all for user control and thus hope that the Frame Averaging tool will be expanded to longer shutter speeds and also to allow different stacking algorithms.

    I guess the Sony SR app uses a different math. I haven't used it nor do I have a compatible camera. But it may have other limitations.

    -Dominique
    Likes 2 Member(s) liked this post

  24. #74
    Senior Member etrump's Avatar
    Join Date
    Jan 2009
    Posts
    1,364
    Post Thanks / Like

    Re: IQ4150 Frame Averaging Comparisons

    My understanding is the averaging is happening on chip with purely raw data, in real time before it is read from the chip and piped to the control system.

    Substantially different process than interpolating during raw conversion then averaging.

    Quote Originally Posted by Christopher View Post
    Well Photoshop does it, Sony does it... so shouldn’t be hard for Phase One... or perhaps it is.

    Besides that. There are always scenes where one cannot get around not blowing something. And it should be possible.
    Ed Cooley

    Visit My Website

  25. #75
    Member
    Join Date
    Jan 2019
    Location
    STL Missouri
    Posts
    135
    Post Thanks / Like

    Re: IQ4150 Frame Averaging Comparisons

    Quote Originally Posted by SCHWARZZEIT View Post

    I think the Frame Averaging tool is powerful enough that it deserves a proper description in the manual with warnings about the pitfalls that the user might face. But I'm all for user control and thus hope that the Frame Averaging tool will be expanded to longer shutter speeds and also to allow different stacking algorithms.


    -Dominique

    Amen. Phase One I hope you are listening. Great tool, but need more input so we can make the most of it, and directly from Phase One, not dealers, not users.

    R
    Likes 1 Member(s) liked this post

  26. #76
    Senior Member
    Join Date
    May 2013
    Location
    SF Bay Area
    Posts
    296
    Post Thanks / Like
    Images
    3

    Re: IQ4150 Frame Averaging Comparisons

    Quote Originally Posted by Christopher View Post
    Well Photoshop does it, Sony does it... so shouldn’t be hard for Phase One... or perhaps it is.

    Besides that. There are always scenes where one cannot get around not blowing something. And it should be possible.
    Photoshop does it, but it produces a TIFF as a result not a RAW. You have to modify the raw images before merging them, and you have to manage many images instead of only one. Much less convenient in my book.

    Sony does it, but only with its Playmemory app. Very cumbersome IMO, and it does not work on a7rIII, a7rIV, or a9.

    Several non-Sony brands implement multiple exposures well and produce RAW images like Phase One, but they heavily limit the number of possible exposures to be averaged (4-9).

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •