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10-31-2022, 05:37 AM   #1
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K-3 monochrome

Assume for giggles that I had a K-3 debayered. Are there any obvious and not-so-obvious menu changes I should make?

10-31-2022, 09:47 AM   #2
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Obviously, you'll want to save the RAW file -- any JPEG is going to be a little strange as the camera assumes that all the former "blue" pixels are seeing something different from all the former "green" pixels, etc.

The part that might be non-obvious (and in need of a bit of experimentation) is the white balance and color setting. Unless you have some special software that opens the RAW file as if it were a non -Bayer filter camera (this software must blatantly ignore parts of the EXIF that encode the Bayer filter geometry and color response), then something somewhere is going to interpret the supposedly RGB pixels of the RAW file in some way that assumes some sort of color filter properties, white balance and some sort of appropriate weighting of the color channels to make a monochrome image.

In most Bayer filter cameras, the blue channel is less sensitive than the red channel which is less sensitive than the green channel which means creating an RGB image requires multiplying the RAW data to correct for the differences in sensitivity. Also, each color channel has some cross-sensitivity (e.g., the blue pixels do pick up a little green and red light) which means that estimating the true amount of blue in the subject requires subtracting a bit of the amounts seen in the red and green. All of these gains and cross-corrections come at the expense a bit of noise (which can't be helped if the goal really is an RGB image taken with a Bayer filter sensor). But, for monochrome images from a deBayered sensor, you'd like to avoid all that noise-adding color math.

I've never messed with a deBayered camera so it's not clear how to avoid this issue. But maybe a custom white balance could help. With the Bayer filter removed, the blue pixels will see a lot more light as will the red pixels compared to the Bayer filtered condition. It's as if the lighting of the scene was pushed to the magenta end. Maybe the white balance can help equalize the gains.

Another possibility is to dig into the EXIF and manually change the color matrix to eliminate the gains and cross-terms.

The acid test for whatever you try will be in taking very high ISO images of something detailed like a printed page or test target. The different tricks in white balance, color matrix, and monochrome conversion should lead to changes in the final image noise (and maybe effects in sharpness).

Good luck and let us know how it goes -- I'm very curious.
10-31-2022, 11:13 AM   #3
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Thank you sir! Helpful.

I'm curious though if there are camera menu choices I need to change.
10-31-2022, 12:15 PM - 2 Likes   #4
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QuoteOriginally posted by gatorguy Quote
Thank you sir! Helpful.

I'm curious though if there are camera menu choices I need to change.
I would say you do not need any changes in menu if you want to shoot RAW exclusively. In case you shoot RAW+ you can use Digital filters. Extract color does not work for mono sensor. Toy Camera (works) - adds 4 types of tonning, Retro (works) can add frame for picture and toning from blue to brown in 7 steps, High contrast (works) has 5 levels, Shading (works) has 4 levels and 7 steps for vigneting, Invert color (works) - does mono inversion (like x-ray), Unicolor bold (does not work on mono), Bold monochrome (woks) - 3 levels of adjustment. All these effects are for JPEG files.
On Monochrome camera you can use ISO Sensitivity Auto up to 25600. In case of right exposition ISO 25600 files are usable.
High ISO NR - OFF
Slow shutter speed NR - ON (Auto)
Live View - Histogram display ON. I always use histogram to see highlights clipping. Or you can use Highlight allert to prevent highlight clipping.
LCD Display Settings: I like slight adjustment of Blue-Amber scale to Amber side (+3) because K-3 has blueish (cold) LCD color in monochrome.
I use Monochrome color profile as well instead of Natural, Bright etc.
White balance - set it as Custom WB using 18 percent gray color.


Last edited by Medex; 10-31-2022 at 01:31 PM.
10-31-2022, 01:52 PM   #5
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QuoteOriginally posted by Medex Quote
I would say you do not need any changes in menu if you want to shoot RAW exclusively. In case you shoot RAW+ you can use Digital filters. Extract color does not work for mono sensor. Toy Camera (works) - adds 4 types of tonning, Retro (works) can add frame for picture and toning from blue to brown in 7 steps, High contrast (works) has 5 levels, Shading (works) has 4 levels and 7 steps for vigneting, Invert color (works) - does mono inversion (like x-ray), Unicolor bold (does not work on mono), Bold monochrome (woks) - 3 levels of adjustment. All these effects are for JPEG files.
On Monochrome camera you can use ISO Sensitivity Auto up to 25600. In case of right exposition ISO 25600 files are usable.
High ISO NR - OFF
Slow shutter speed NR - ON (Auto)
Live View - Histogram display ON. I always use histogram to see highlights clipping. Or you can use Highlight allert to prevent highlight clipping.
LCD Display Settings: I like slight adjustment of Blue-Amber scale to Amber side (+3) because K-3 has blueish (cold) LCD color in monochrome.
I use Monochrome color profile as well instead of Natural, Bright etc.
White balance - set it as Custom WB using 18 percent gray color.
All of that is very helpful! Thank you for your thoroughness.
04-23-2023, 11:53 PM   #6
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QuoteOriginally posted by Medex Quote
In case you shoot RAW+ you can use Digital filters. Extract color does not work for mono sensor.


All these effects are for JPEG files
  • Toy Camera (works) - adds 4 types of tonning,
  • Retro (works) can add frame for picture and toning from blue to brown in 7 steps,
  • High contrast (works) has 5 levels,
  • Shading (works) has 4 levels and 7 steps for vigneting,
  • Invert color (works) - does mono inversion (like x-ray),
  • Unicolor bold (does not work on mono),
  • Bold monochrome (woks) - 3 levels of adjustment.

On Monochrome camera you can use ISO Sensitivity Auto up to 25600. In case of right exposition ISO 25600 files are usable.
  • High ISO NR - OFF
  • Slow shutter speed NR - ON (Auto)
  • Live View - Histogram display ON. I always use histogram to see highlights clipping. Or you can use Highlight allert to prevent highlight clipping.
  • LCD Display Settings: I like slight adjustment of Blue-Amber scale to Amber side (+3) because K-3 has blueish (cold) LCD color in monochrome.
  • I use Monochrome color profile as well instead of Natural, Bright etc.
  • White balance - set it as Custom WB using 18 percent gray color.
Would be intersting what Pentax did change in the K-3 II monochrome
04-24-2023, 02:00 AM   #7
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QuoteOriginally posted by angerdan Quote
Would be intersting what Pentax did change in the K-3 II monochrome
I did not have this new camera K-3III Monochrome. Probably new upcoming users will shed some light or information can be extracted from User manual (if it already is published).

02-19-2024, 01:11 PM - 4 Likes   #8
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K-3 with Bayer filter removed

This is to reply to Gatorguy about removing the Bayer filter from a K-3. I bought one from a friend who needed cash and I thought why not since I like B&W. I wanted to see the difference between a mono camera and converting a color RAW image to B&W. I was amazed at the clarity and the contrast of the converted K-3 to mono. I may never convert from a color RAW again. Used the K-3 without the Bayer filter was akin to shooting Kodak PanX with D76. I was in love with B&W again. I shoot in RAW and make adjustments but very few. I could show images SOOC and be happy. I am including an image I took a week ago in low, contrasty light.
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02-19-2024, 05:44 PM - 2 Likes   #9
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QuoteOriginally posted by A10 Quote
This is to reply to Gatorguy about removing the Bayer filter from a K-3. I bought one from a friend who needed cash and I thought why not since I like B&W. I wanted to see the difference between a mono camera and converting a color RAW image to B&W. I was amazed at the clarity and the contrast of the converted K-3 to mono. I may never convert from a color RAW again. Used the K-3 without the Bayer filter was akin to shooting Kodak PanX with D76. I was in love with B&W again. I shoot in RAW and make adjustments but very few. I could show images SOOC and be happy. I am including an image I took a week ago in low, contrasty light.
I'd forgotten about this thread.

So I did end up getting a debayered K3, and what it does for you it did for me too! Loved that camera, and the way using it forced me to think different. I loved it so much I've ended up with a debayered K1.
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