Image Corruption

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Today’s Question: I have attached an image file with color bars at the lower right hand corner. I was wondering if you have seen this before and can identify the source of the problem. I have experienced this probably about three times over the last 6 months. I have a Canon 5D MKIII camera and used my Tokina 16-28mm f2.8 lens for this shot. Is my camera sensor starting to go bad, lens problem, bad memory card, etc.? Any help is appreciated.

Tim’s Quick Answer: The image provided by the photographer who submitted this question demonstrates the classic symptoms of a corrupted capture. This type of issue is generally caused by a problem when the file is written to the card, or when the file is copied to your computer. Thus, the key is to isolate the specific cause of the issue.

More Detail: Identifying the source of file corruption for a digital capture can be a little bit of a challenge, with some misleading information along the way. For example, an uncorrupted image displayed on the camera’s LCD does not necessarily indicate that the image file isn’t corrupted, because what you’re seeing is the JPEG image rendered by the camera, not the actual RAW capture.

It is possible that the source of this problem is the camera itself, the card being used to store the photos, the card reader you are using to download the photos, any of the cables used to connect the camera or card reader, or the computer itself, among other possible causes.

As soon as this sort of issue starts to show up, it is important to try to isolate the problem as quickly as possible. This involves keeping track of what equipment is in use when the problem occurs, and trying to isolate the specific source. So, for example, you can test different cards, different card readers, and possibly even different cameras to try to identify the cause.

Once this sort of issue arises I’m not comfortable trusting the components involved. To be sure, it is possible that the corruption was created by ejecting a card from the camera before the file had been completely written. But if you’re confident that wasn’t an issue, there is likely a hardware problem at play. I would tend to stop using any card that exhibits this sort of corruption. But again, the key is to test out different hardware to isolate the specific source of corruption. This can be a time-consuming process, especially if the problem only occurs sporadically. But in most cases if the problem is not a matter of user error it is caused by hardware problems, so you’ll want to find the source as quickly as possible so you can capture new images with confidence.

You can learn more about the issue of corrupted captures in my article titled (appropriately enough) “Corrupted Captures” that appeared in the April 2015 issue of Pixology magazine. If you’re not already a subscriber you can sign up at http://pixologymag.com, and I would be happy to send you the back issues at no additional cost.