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How to Fix Sensor Tiling With Photoshop

diggles

Well-known member
My first choice for photo editing is ACR/Photoshop. While looking for a way to apply LCC corrections without using C1/Phocus/Lightroom I ran across this article:

The steps outlined in the article do a good job of fixing vignetting, but didn't really help with colorcast. At first I was a bit frustrated, but then I wondered if this method could work to fix sensor tiling. I've tried it on 4 different images, 1 taken with the Digaron 28HR and 3 taken with the Digitar 43XL. Initial tests are quite promising.

Here are the steps I took with example images and screenshots:

STEP 1
RAW CAPTURE: Hasselblad CFV II 50C (cmos 50mp sensor), Digitar 43XL, and the WRS 1600 with 20mm of camera fall
01-43xl-tiling-fix-raw.jpg
RAW CAPTURE 100% Crop
02-43xl-tiling-fix-raw-crop.jpg
As you can see this combo creates one hell of a mess. Tiling is very pronounced and streaky noise is noticeable in the sky.

Matching LCC Frame
03-43xl-tiling-fix-lcc.jpg

STEP 2
Process files in Phocus and export 16bit tiffs to edit in Photoshop. With Phocus you are able to apply the LCC correction to the LCC reference file and export the corrected image as a 16bit tiff. This step is critical in making this work. Not sure it would work without having a corrected LCC reference file to work with. I'm not sure if Capture One or Lightroom allows you to export the corrected LCC reference file or not.

Corrected image using Scene Calibration in Phocus exported as 16bit tiff file
04-43xl-tiling-fix-export-image.jpg

Corrected image 100% crop
05-43xl-tiling-fix-export-image-crop.jpg

Corrected LCC reference image
06-43xl-tiling-fix-export-lcc.jpg

Phocus did a pretty good job of cleaning the image up. The extreme color cast is gone, but the sensor tiling and streaky noise is still present.

STEP 3
Create a photoshop file with the corrected image as the base layer. Add the corrected LCC reference image in a group above. Then create a Levels adjustment layer above the corrected LCC reference image. In the Levels control, hold down the option (alt on a PC) key and move the highlight (white) triangle slider left until you start to see highlights being clipped. The highlight triangle will end up being just to the right of the histogram mass.

Screenshot of the layer configuration and histogram
07-screenshot-levels.png

After making the levels adjustment, this is what the LCC reference image should look like
08-43xl-tiling-fix-lcc-levels.jpg


Step 4
Change the blending mode of the group with the LCC reference image and Levels adjustment layer to Divide and fine tune if needed.

Screenshot of blending mode changed to Divide
09-screenshot-divide.png

That's it. I'll add the final images + 100% crops in a follow up comment.

Note: With this image I did not need to fine tune the settings. With a different image I tested, there was still a faint outline of the tiling present after changing the blending mode to Divide. What I did to fix it is move the shadow (black) triangle in the levels control to the right until the tiling disappeared.
 
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diggles

Well-known member
Here are the final images with 100% crops.

After applying the levels adjustment to the corrected LCC file and change the blend mode to Divide
10-43xl-tiling-fix-lcc-divide.jpg

100% Crop
11-43xl-tiling-fix-lcc-divide-crop.jpg

After making final corrections to the image in Photoshop
12-43xl-tiling-fix-final.jpg

100% crop
13-43xl-tiling-fix-final-crop.jpg

The tiling and streaks are gone. There is still noise in the sky, but there are other ways to fix that.

I'm not sure if this will work on any image, but so far it has worked for me on 4 different scenes. This example is the most extreme that I tried it on. If you have any images with tiling, try to see if this fixes it.
 

dchew

Well-known member
Warren,
I am so going to try this with a few 35xl images. Thank you very much for posting!

BTW, you can export a corrected LCC in C1 just like a normal image.

Ciao,
Dave
 

diggles

Well-known member
Good to know that you can export a corrected LCC in C1, I assumed so, but didn't know for sure.

Hope it works with the 35xl too. Post an example when you get a chance :)
 

usm

Active member
Warren,
I did a quick test with my CFVii50c and the Schneider XL35 - it works with the sensor tiling problem - really great - thank you!!

But it doesn't help with the pattern problem. Did you use the "Remove Checkerboard Patterns" in the "noise filter" tool?
I can see red colorshift on your untouched image in top left corner. Is this just a color shift or are the strange patterns?
Like this:
SK35XL-210720-007.jpg


Mario
 

diggles

Well-known member
I did a quick test with my CFVii50c and the Schneider XL35 - it works with the sensor tiling problem - really great - thank you!!

But it doesn't help with the pattern problem. Did you use the "Remove Checkerboard Patterns" in the "noise filter" tool?
Hey Mario, I'm happy to hear the sensor tiling fix worked for you, great news! I didn't use the "remove checkerboard patterns" option. The pattern shown in your example wasn't present in my image. I have seen that pattern in images before, but didn't realize that there is a checkbox in Phocus to mitigate it. Good to know.

I'm curious under which situations you've ran across this pattern? I ran across this pattern while doing some tests when I first got the lens. For me, it was when shifting left and right 12mm or more while the camera was in vertical position. I deleted those files, but I'm going to try and recreate it so I can see how well the "Remove Checkerboard Patterns" works for me.

"Remove Checkerboard Patterns" will work fine
Hey Kinglang, do you have a "Remove Checkerboard Patterns" before and after example you would be up for sharing?
 

usm

Active member
The "remove checkerboard patterns" option works for me, but it is strange:
Movement is always 15mm which is the max on my factum:

Shifted up and down, Sensor horizontal - I have to turn it OFF! When turning ON the pattern is present.
Shifted up and down, Sensor vertical - I have to turn it ON!
Shifted left and right, Sensor vertical - I have to turn it ON! But the patter is NOT removed completely.
Shifted left and right, Sensor horizontal - I have to turn it ON! Pattern is removed.

Shifted right, Sensor vertical and shifted up, Sensor horizontal is the same part of the lens and the same part of the sensor.
For me, it is a bug in Phocus.
 

diggles

Well-known member
That is strange. Do you know if the checkerboard patterns only show up on Hasselblad files? Or do they show up on other camera files that use the same 50mp CMOS sensor?
 

kinglang

Member
an example, shot with HR70 & Hassy back,It is more likely to appear when the moving range is greater than 15mm.Checkerboard patterns are also sometimes visible from back screen playback when using P1 back, but they disappear when imported into C1. So I think C1 automatically eliminates them by default.

20220416134410-horz.jpg
 

diggles

Well-known member
Thank you for sharing this Kinglang. I wasn't expecting it to be an issue with the HR and 70mm focal length. I was assuming it was a side effect of the Schneider wide angle lenses.
 
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