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Thread: RAW Merrill

  1. #1
    Senior Member Malina DZ's Avatar
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    RAW Merrill

    Recently I stumbled upon a X3F Merrill raw image output thanks to RawTherapee converter. I heard Foveon files are noisy even at iso 100, but had no idea how much. Noise can be tamed quite well with either X3F_Tools or RawTherapee, but a lens color cast is something only SPP can rid of completely at the moment. Lomography fans may find Merrill processing in RT quite delightful.
    Are there any profiles available for DP Merrills to remedy color casts?
    I tried x3f_wrapper (https://github.com/Kalpanika/x3f_wrapper). It does a good job, noticeably better than a RawTherapee output, but still not a match to SPP in this regard.
    I'm quite content with the SPP processing, just wish I could get those cropped 102x66 pixels back
    Below is a comparison between SPP and RawTherapee conversion of a DP1M file at iso100 (DPreview test scene) to show how much color cast there is in uncooked X3F:

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    Re: RAW Merrill

    Quote Originally Posted by Malina DZ View Post
    ...to show how much color cast there is in uncooked X3F..
    and how this cast is spread, some parts are green, some magenta,
    btw pixel count is different^^
    A dude bought an adapter to use old glass on his SD1 and the images showed the center with heavy magenta cast and the rest with green cast, or vice versa;
    he wasnt able to correct this in a satisfying way and as a printer he is very good in fixing pics.
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    Senior Member Malina DZ's Avatar
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    Re: RAW Merrill

    Quote Originally Posted by foveon View Post
    btw pixel count is different^^
    Not just the count, but the FOV as well! Why is this ~2% crop applied across all Merrill X3F files in SPP?

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    Re: RAW Merrill

    Having both the DP1M and 2M and SD1 I have often thought colour casts are more a problem with the DP's than the SD which seems to me to render colours better. An example....sometimes there is a magenta cast to blue skies at the edge of the image with the DP1M. It is much less but nevertheless similar to the green cast above. Could it have something to do with the incident light path from entry point at the lens to the sensor being different? I would be interested to see a similar investigation of an SD RAW file if one exists?

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    Re: RAW Merrill

    Quote Originally Posted by Malina DZ View Post
    I'm quite content with the SPP processing, just wish I could get those cropped 102x66 pixels back
    So, if I understand correctly, a DP Merrill image from SPP is less than 4704x3136px, unlike the SD1 Merrill?

    If you want it all, RawDigger can give you it all, including the masked-off area of the sensor.

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    Senior Member Malina DZ's Avatar
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    Re: RAW Merrill

    Quote Originally Posted by digi2ap View Post
    ...Could it have something to do with the incident light path from entry point at the lens to the sensor being different? I would be interested to see a similar investigation of an SD RAW file if one exists?
    It seems like the closer a rear lens element gets to the sensor, the more color cast there is in Merrill files. It is a guess since I don't have these measurements for DPMs.
    Imaging Resource has raw files for both DP1M & SD1M.

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    Senior Member Malina DZ's Avatar
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    Re: RAW Merrill

    Quote Originally Posted by xpatUSA View Post
    So, if I understand correctly, a DP Merrill image from SPP is less than 4704x3136px, unlike the SD1 Merrill?

    If you want it all, RawDigger can give you it all, including the masked-off area of the sensor.
    SPP outputs Merrill X3F files at the same 4704x3136px resolution for all 3 DPMs and SD1M.
    I wish RawDigger did correct color cast in DPMs as well.

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    Re: RAW Merrill

    Quote Originally Posted by Malina DZ View Post
    SPP outputs Merrill X3F files at the same 4704x3136px resolution for all 3 DPMs and SD1M.
    Yes, I'm aware of that. FastStone Viewer actually adds 224x168 to an SD1M image but their raw conversion is done by DCraw and is crap for Merrills.

    The default conversion For Merrills in RawTherapee is quite poor and has a lot of USM (250) enabled. One way to go with RT, which I never bothered with, is to work up a .pp3 profile and save it for re-use.

    Have you tried Affinity Windows beta which was out for trial recently? Nobody on DPR jumped for joy though . . . I found that they ignored the Merrill ISO setting - so images at 200 ISO and up got darker and darker, leaving the User to do what SPP does automatically.

    I wish RawDigger did correct color cast in DPMs as well.
    A pity but RawDigger, as you know, is for analyzing raw data. Just as SPP is for the best possible conversion but not the finest all-singing all-dancing post processor.

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    Re: RAW Merrill

    Quote Originally Posted by Malina DZ View Post
    It seems like the closer a rear lens element gets to the sensor, the more color cast there is in Merrill files. It is a guess since I don't have these measurements for DPMs.
    The cast might be due to the hot mirror which is mounted on the sensor, unlike the SD1. Once, I tried shooting with the SD1M dust cover removed and bought a B+W 486 UV/IR blocking filter for the lens. Unfortunately, at wide angle (17mm) that filter gave a similar color cast even in SPP - because it is a dichroic type, quite sensitive to the incident angle of the light. About 60 degs or less - forget it!

    Another theory is that the DP Merrills have the exactly the same micro-lenses as the SD sensor with Sigma/Foveon choosing fix it in software. This is a different philosophy to that for earlier models where the DP models (DP13 sensor) have different micro-lenses than the SD's (F13 sensor).

    For these and other complications, I have reverted to pre-Merrill, non-AFE Sigmas and now lead a more simple life.
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    Re: RAW Merrill

    Quote Originally Posted by xpatUSA View Post
    The cast might be due to the hot mirror which is mounted on the sensor, unlike the SD1. Once, I tried shooting with the SD1M dust cover removed and bought a B+W 486 UV/IR blocking filter for the lens. Unfortunately, at wide angle (17mm) that filter gave a similar color cast even in SPP - because it is a dichroic type, quite sensitive to the incident angle of the light. About 60 degs or less - forget it!

    Another theory is that the DP Merrills have the exactly the same micro-lenses as the SD sensor with Sigma/Foveon choosing fix it in software. This is a different philosophy to that for earlier models where the DP models (DP13 sensor) have different micro-lenses than the SD's (F13 sensor).

    For these and other complications, I have reverted to pre-Merrill, non-AFE Sigmas and now lead a more simple life.
    hmmmm . . . Thread-stopper Ted strikes again!!

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    Senior Member Malina DZ's Avatar
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    Re: RAW Merrill

    Quote Originally Posted by xpatUSA View Post
    hmmmm . . . Thread-stopper Ted strikes again!!
    Ted, unfortunately, there is nothing for me to add due to my lack of knowledge on color cast matter. I doubt anyone will invest their time and resources to create a better X3F file editor than SPP. Even Sigma does not introduce improvements and new features for Merrill files in SPP updates. No FW updates either.
    Nonetheless, I keep on shooting with DPMs and enjoy the IQ that a combination of a leaf shutter and Foveon sensor delivers.

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    Re: RAW Merrill

    Quote Originally Posted by Malina DZ View Post
    Ted, unfortunately, there is nothing for me to add due to my lack of knowledge on color cast matter. I doubt anyone will invest their time and resources to create a better X3F file editor than SPP. Even Sigma does not introduce improvements and new features for Merrill files in SPP updates. No FW updates either.
    Nonetheless, I keep on shooting with DPMs and enjoy the IQ that a combination of a leaf shutter and Foveon sensor delivers.
    There was a user who created flat-field corrections for all the dp Merrills. (for DNG)
    The Kalpanika-team implied them into the x3f-wrapper. After a few hickups in the beginning it worked quiet well for me.
    I still prefer the output from SPP though.

    Also the sd1 RAW (or SPP) does apply flat-field corrections for older Sigma lenses. Otherwise you would get images with green corners and magenta center.
    I'm pretty sure this is not necessary anymore with new Sigma lenses as their construction is more telecentric and the lightwaves hit the sensor more straight. (90)


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    BTW: Here an older post from Oz with this topic: https://www.dpreview.com/forums/thread/3568214
    flickr
    500px
    Blog (Foveon related)
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    Senior Member Malina DZ's Avatar
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    Re: RAW Merrill

    Quote Originally Posted by Stoneage View Post
    There was a user who created flat-field corrections for all the dp Merrills. (for DNG)
    The Kalpanika-team implied them into the x3f-wrapper. After a few hickups in the beginning it worked quiet well for me.
    The flat-field correction option has only been implemented for Mac, not PC, hasn't it? I tried x3f-wrapper for PC a while ago and don't remember running extra commands in cmd for color cast correction. Regardless, I also preferred IQ generated by SPP to Kalpanika's DNG conversion results.

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    Re: RAW Merrill

    Quote Originally Posted by Malina DZ View Post
    The flat-field correction option has only been implemented for Mac, not PC, hasn't it?
    Oh, really? I didn't know that.
    hm, but it should be no problem to implement it in the PC version.

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    Senior Member Malina DZ's Avatar
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    Re: RAW Merrill

    Quote Originally Posted by xpatUSA View Post
    Have you tried Affinity Windows beta which was out for trial recently? Nobody on DPR jumped for joy though . . . I found that they ignored the Merrill ISO setting - so images at 200 ISO and up got darker and darker, leaving the User to do what SPP does automatically.
    I gave Affinity a try. Unfortunately, it also does not cope with the color cast, and, as you pointed out, it does not adjust exposure for ISO values above 100. Verdict: uninstallation.

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