Tech cam & dealing with magenta cast

[Pemihan]

I'm not the biggest shark when it comes to post processing so I would be interested to learn what you do to get rid of the residual magenta cast, especially in the sky, that the LCC process in C1 doesn't clean up.

I can of course desaturate magenta in C1, but if you have magenta/red anywhere else in the image that doesn't work very well. It can unfortunately not be done on a separate layer, which would have been great.

As I primarily do B&W it hasn't really been a problem for me but as I'm beginning to do some color work as well it some times become a problem. I'm sure it is a pretty easy task to clean it up when you know what to do :banghead:

Thanks
Peter

 

[danlindberg]

In a case like you describe, only changing colour tone in one part of the image I simply make another layer and make they change in this new layer to that part. Then use the delete brush to bring up the underlaying layer again for the rest o fthe image. Getting closer to the altered area making the brush quite soft and playing with opacity to make the transition smooth.

 

[algrove]

Sometimes creating a graduated layer in C1 can work at times while reducing magenta in that layer.

 

[Pemihan]

In a case like you describe, only changing colour tone in one part of the image I simply make another layer and make they change in this new layer to that part. Then use the delete brush to bring up the underlaying layer again for the rest o fthe image. Getting closer to the altered area making the brush quite soft and playing with opacity to make the transition smooth.

Thanks Dan, I assume that's in Photoshop?

 

[Pemihan]

Sometimes creating a graduated layer in C1 can work at times while reducing magenta in that layer.

Thanks, I will have to give that a closer look.

 

[Paul2660]

Agree on the use of a graduated layer. But in C1 instead of photoshop

C1’s layer are very powerful and each allows a separate white balance adjustment.

Your post brings back a lot of memories and is one reason I moved back to the XF. Just got tired of the magenta issues in a sky on shifts.

Guess the IQ4150 will fix a lot of that.

Paul C

 

[algrove]

Yes, as I mentioned use graduated layer in C1.

 

[danlindberg]

Thanks Dan, I assume that's in Photoshop?

Indeed, in photoshop.

 

[dougpeterson]

I can of course desaturate magenta in C1, but if you have magenta/red anywhere else in the image that doesn't work very well. It can unfortunately not be done on a separate layer, which would have been great.

Color Edits can be made on a separate layer. Perhaps you got confused when you saw that the preview function shows the color throughout the image, not just limited to the local area. But the end effect is indeed limited by the mask.

Easiest adjustment to your workflow would be to upgrade to an IQ4 150mp which produces vastly less color cast .

 

[jotloob]

. . . .

Easiest adjustment to your workflow would be to upgrade to an IQ4 150mp which produces vastly less color cast .

Unbelievable . I hope this is NOT Dougs serious opinion .

 

[Pemihan]

Unbelievable . I hope this is NOT Dougs serious opinion .

I take it as as a not so serious humorous comment, hence the smiley at the end. But Doug is right about the fact that the 150 produces much less color cast, but that is NOT in the cards for me in the foreseeable future. Also I really don't need 150MP, 80 or 100 are more than enough for me (famous last words).

 

[jotloob]

Yes Peter I understand the humorous comment .
Best , of course , would be to produce digital backs which produce images without any color cast .
I have never seen a color cast (beside the LCC correctable cast) with my HASSELBLAD backs .

 

[Pemihan]

Yes Peter I understand the humorous comment .
Best , of course , would be to produce digital backs which produce images without any color cast .
I have never seen a color cast (beside the LCC correctable cast) with my HASSELBLAD backs .

The vague uncorrectable cast I sometimes see is with considerable shifts 10mm+ (rise) where there sometimes is a faint magenta cast left in the corners of the sky. With little to no shift it is totally correctable.

 

[dougpeterson]

Unbelievable . I hope this is NOT Dougs serious opinion .

Yes Peter I understand the humorous comment .
Best , of course , would be to produce digital backs which produce images without any color cast .
I have never seen a color cast (beside the LCC correctable cast) with my HASSELBLAD backs .

The vague uncorrectable cast I sometimes see is with considerable shifts 10mm+ (rise) where there sometimes is a faint magenta cast left in the corners of the sky. With little to no shift it is totally correctable.

Peter (Pemihan): perhaps you could post some example images (before/after LCC) along with the lens/movement spec so that others who don't have experience with P1 backs on a tech camera can understand the scope of the issue. Otherwise, as you can see from Jotloob's response, someone might mistakingly think that P1 backs have more of a color cast issue than other brands, when the opposite is true. Perhaps you could even share a matched raw and LCC capture so that others (including myself) can show how we would handle the issue you point out.

Jotloob: P1 is the leader when it comes to tech camera LCC. A lot of R+D effort has gone into the LCC tool in C1 to refine its accuracy and utility. However, if you take a high-enough resolution back, with a wide-enough lens (especially Schneider symmetrical lenses), and apply enough movement then the LCC tool may not be able to fully correct the cast, and will either leave a slight residual cast or reduced saturation at the edge of the frame. If you put another brand of back with the same resolution through the same high-stress test it would do even less well. If you've never seen this with your back that means you're using a lower-resolution back, a less problematic lens model, or less movement. It's also possible you haven't scrutinized the image closely enough (even if you're a careful and expert shooter), since the amount of residual cast we are talking about can often be extremely minor and easy to miss without looking specifically for it.

As to solving this by buying an IQ4 I'm poking at Peter in a friendly way. Technically this would solve his problem since the IQ4 150mp produces drastically less color cast, but of course this is like someone asks "I have three cars, but only a two-car garage, which one should I keep to resolve this quandary?" and answering "Buy a house with a bigger garage ". It's technically true, but not really a serious answer, at least the specific question asked. My more serious answer was directly above it: the Capture One Color Editor (including "uniformity") can be applied locally and is good for this sort of thing.

 

[dougpeterson]

Also I really don't need 150MP, 80 or 100 are more than enough for me (famous last words).

Despite marketing always leading with pixel count (including marketing I help with, to be fair), resolution would be the fourth or fifth reason on my list of reasons to upgrade to an IQ4 150mp.

We've been working with the 2nd-generation pre-production unit in Texas all week and the feature set (live focus peaking, live histogram, live raw histogram, live clipping indicator), responsively (faster live view, faster navigation of the image), improved image on the LCD ("C1 inside" leading to better pixel sharpness and generally more accurate on-screen image), and new gestures (swipe up, swipe down, pinch to zoom) all make shooting faster, more accurate, and more enjoyable.

Even those are secondary to the #1 reason on my list, and not just because it's relevant to this thread: drastically enhanced tech camera performance/workflow. I love tech cameras. I love them in a slightly irrational way; I just enjoy shooting with them more than with other kinds of cameras. The IQ4 is going to be a huge step forward for tech camera users.

I suspect more people will enjoy the increased resolution than you'd think. But I don't think it deserves the "first billing" it gets; "150mp" is literally in the name. Then again "IQ4 Really Great Feature Set with Improved Performance (Especially on a Tech Camera)" is a distinctly less manageable name.

 

[kdphotography]

Unbelievable . I hope this is NOT Dougs serious opinion .

IQ4 150MP would have been my serious (ok, not so serious) opinion. :ROTFL:

Sit tight and wait for Dante to work his magic.

Usability on a tech cam gives me pause for thought, even though I'm not sure I can justify upgrading to the IQ4 150. Resolution is secondary for sure.

Ken

 

[jotloob]

Peter (Pemihan): perhaps you could post some example images (before/after LCC) along with the lens/movement spec so that others who don't have experience with P1 backs on a tech camera can understand the scope of the issue. Otherwise, as you can see from Jotloob's response, someone might mistakingly think that P1 backs have more of a color cast issue than other brands, when the opposite is true. Perhaps you could even share a matched raw and LCC capture so that others (including myself) can show how we would handle the issue you point out.

Jotloob: P1 is the leader when it comes to tech camera LCC. A lot of R+D effort has gone into the LCC tool in C1 to refine its accuracy and utility. However, if you take a high-enough resolution back, with a wide-enough lens (especially Schneider symmetrical lenses), and apply enough movement then the LCC tool may not be able to fully correct the cast, and will either leave a slight residual cast or reduced saturation at the edge of the frame. If you put another brand of back with the same resolution through the same high-stress test it would do even less well. If you've never seen this with your back that means you're using a lower-resolution back, a less problematic lens model, or less movement. It's also possible you haven't scrutinized the image closely enough (even if you're a careful and expert shooter), since the amount of residual cast we are talking about can often be extremely minor and easy to miss without looking specifically for it.

As to solving this by buying an IQ4 I'm poking at Peter in a friendly way. Technically this would solve his problem since the IQ4 150mp produces drastically less color cast, but of course this is like someone asks "I have three cars, but only a two-car garage, which one should I keep to resolve this quandary?" and answering "Buy a house with a bigger garage ". It's technically true, but not really a serious answer, at least the specific question asked. My more serious answer was directly above it: the Capture One Color Editor (including "uniformity") can be applied locally and is good for this sort of thing.

Thank you Doug for your extensive comment . Much appreciated .

My widest lens for ALPA is the HRDIGARON-s 4,5/28mm + also the HRDIGARON-w 4,0/40mm .
In regard to the Q4 150 back my HB CFV50 seems to be a "fat pixel" back , but serves me well and the resolution is just fine for what I shoot . Normal LCC handling in PHOCUS produces very good images .