There is here a tiny twist here. The raw images (.dng-files) produced by picamera2 have additional meta data attached which might affect the way the software you are using for raw development might interpret the pixel data.
Specifically, there are at least two entries which come to my mind:
A few raw converters use this information to present you a first (viewable) version of your .dng-file. In Raw Therapee for example, this interpretation of the raw data is selected in the "Color Management" tab with the checkbox "Camera standard". A similar entry is available in the raw input unit of daVinci Resolve, etc. It's probably the first choice of any standard raw software for showing you a raw file on your computer display.
Of course, you can roll you own CCM (or white balance multipliers for that matter). One other possibility is to use .dcp-profile files - which exist at least for the HQ camera. How to do this depends on your program of choice for developing the raw into something usable.
Summarizing in general terms: there is more data (a lot more) in the .dng-files than meets the eye, and it will be used by your raw software to cast the raw data (which looks aweful) into something viewable. If your question aims only at what affects the raw pixeldata contained in the .dng-file, indeed exposure time, gain and image orientation are the main culprits. However, most .dng-files are further processed ("developed") into .png- or tiff-files viewable on a computer monitor. In this case, other data contained in the .dng-file plays a vital role.
Specifically, there are at least two entries which come to my mind:
- the "AsShotNeutral"-tag: basically the white balance information (multiplier) for the image, estimated by libcamera at the time of picture taking
- Image Tag 0xC621: this is the CCM (Compromise Color Matrix) that libcamera came up with at the time of shooting the image and which was/would be used to create the .jpg. Note that standard .dng-files do feature normally two CCMs (or even more), so the .dng-files produced by picamera are special, in a sense.
A few raw converters use this information to present you a first (viewable) version of your .dng-file. In Raw Therapee for example, this interpretation of the raw data is selected in the "Color Management" tab with the checkbox "Camera standard". A similar entry is available in the raw input unit of daVinci Resolve, etc. It's probably the first choice of any standard raw software for showing you a raw file on your computer display.
Of course, you can roll you own CCM (or white balance multipliers for that matter). One other possibility is to use .dcp-profile files - which exist at least for the HQ camera. How to do this depends on your program of choice for developing the raw into something usable.
Summarizing in general terms: there is more data (a lot more) in the .dng-files than meets the eye, and it will be used by your raw software to cast the raw data (which looks aweful) into something viewable. If your question aims only at what affects the raw pixeldata contained in the .dng-file, indeed exposure time, gain and image orientation are the main culprits. However, most .dng-files are further processed ("developed") into .png- or tiff-files viewable on a computer monitor. In this case, other data contained in the .dng-file plays a vital role.
Statistics: Posted by cpixip — Fri Apr 05, 2024 2:23 pm