Why do some Canon EOS R RAW files show a random discolored pixel row?
Asked 7/29/2021
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2 answers
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I’m seeing an intermittent issue on a Canon EOS R shooting RAW (.CR3): about 5 images out of roughly 2400 have a single discolored horizontal row. The row is not always in the same position, can be magenta or otherwise color-shifted, and may span part or most of the frame. It appears in the RAW file itself when viewed directly from the SD card on a computer, so it does not seem related to import software.
Details:
- Camera: Canon EOS R, firmware 1.8
- File type: RAW (.CR3)
- Lenses used in affected images: Tamron 150-600mm G2 and Tamron 70-300mm VC
- Same camera also used with other EF/RF lenses without visible incidents
- Occurred across 3 different SanDisk Ultra 32GB SD cards
- Sometimes happens within a burst, affecting only one frame
Because the row position changes from image to image, it doesn’t seem like a normal hot/stuck pixel issue. What is the most likely cause: sensor, lens, SD card, firmware, or camera electronics?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
4y ago
2 Answers
2
Summary:
It appears that the corruption consists of periods of low or no blue channel signal.
The examples below show very low blue channel output even when the corruped image appears somewhat blue.
As my crops may include small amounts of adjacent uncorrupted image the blue channel may be fully dead when corrupted.
This seems highly likely to be a camera related error.
The "why" is uncertain, but taking a histogram of various parts several of several of the images shows in the corrupted lines the blue channel is very low in each case.
I'd expect the problem to be in the camera rather than lens or memory card.
(I may be wrong).
Even in your "animal ear" crop where the defective line looks very blue it still has low blue channel
In the photo you posted to web the low blue channel in the corrupr area and quite different result on the adjacent uncorrupted wall can be seen here.
Originally by user6263. Source · Licensed CC BY-SA 4.0
user6263
4y ago
0
Generated from our catalog & community — verify before relying on it.
Most likely: a camera-side electronics fault, not the lens, sensor pixels, or SD card.
Why:
- A true hot/stuck pixel or damaged sensor row would appear in the same place every time. Yours moves around.
- SD card or transfer corruption is unlikely with CR3. Bit errors in compressed RAW usually cause much larger blocky corruption, not a single colored row.
- Community analysis noted the bad row shows abnormally low blue-channel data, suggesting corruption before or during in-camera processing.
- Because CR3 is compressed, visible artifacts around the row imply the data was already wrong before compression, pointing to the camera’s internal data path/buffer/main board rather than the card.
So the strongest explanation is intermittent corruption in the camera’s readout/buffer/main board circuitry or related firmware-level handling inside the camera.
Practical next step: back up examples and have Canon service inspect the body. Test with another card if you want, but based on the symptoms, the camera body is the likely culprit.
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UniqueBot
AI4y ago
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