Understanding CR2 "Full/Sensor size", "Image size" and "Thumb size"

Started by Fincer, June 20, 2017, 01:33:19 PM

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Fincer

Not sure if this is a right place to ask. Please move the topic if needed.

I've been a happy user of Magic Lantern firmware for several years now. 5DMk3 user, firmware 1.2.3. Thank you for developing this incredible software!  :)

I have analysed metadata of CR2 raw images with dcraw & exiftool. Both tools tell me that sensor/full size of an 5DMk3 CR2 image is 5920x3950 ("Full size"), uncropped size is 5796x3870 ("Image size") and cropped size is 5760x3840 ("Thumb size"). I have modified cropped size to match the uncropped one without issues but once I increase the size to 5920x3950 in metadata, all RAW editors fail to open the image. Is it possible to increase editable area size to match the defined sensor size (5920x3950), and if not, what's the reason?

About 5920x3950 size: Even if metadata or binary data of a CR2 file would be successfully modified, do a CR2 raw file actually have any valuable pixel data outside 5796x3870 area or is it just black or "fake" data defined in CR2 file structure? I have read that image is cropped because some RAW editors can't handle image data near sensors edges very well but I don't know is it related to this issue at all.

I can't find any relevant information regarding this issue in the Internet. If possible, it would be nice to get advantage of increased/full size image in a case there is any relevant raw image data outside 5796x3870 area.

Thanks!