Ytdyklly

I have a project in which I'm trying to balance load between several computing devices. These devices are similar and are supposed to have a camera segment. Device captures an image and then process the image.

For simplicity I want to consider the load as the number of the images waiting on the process queue, but this requires the images to be the same size and have the same specifications.

So my question is that do the images of the same camera have the same size? I know that compressing the images and converting them to .jpeg format, will probably change their size, but how about raw images of the same camera? Do raw images have the same size?

Most digital cameras use lossless compression with raw files. That means the size of raw files from the same camera is somewhat content dependent.

The more detail and different colors a scene contains, the larger the file will be. The more homogeneity a scene contains, the smaller the file will be. The degree of the differences will also be governed by differences in things such as noise in dark areas (noise usually adds to a file size by creating a greater number of unique brightness levels).

A picture being worth a thousand spreadsheet cells, here is an histogram of the size of the RAW files from my camera for 2018 (EOS 70D, 20Mpx). Sizes are in 1000's of K (not really MB).

For the mathematically inclined:

Average:    24538

Median:     24300   

Std dev.:    2119

This may be camera-dependent, but for my Canon EOS 7D Mark II, different raw images are definitely not the same size:

# ls -l *.cr2

-rwx------ 1 tew tew 23868042 Jan 21 10:59 20190121105920-6996.cr2

-rwx------ 1 tew tew 24408037 Jan 21 11:07 20190121110757-7002.cr2

-rwx------ 1 tew tew 25928707 Jan 21 11:08 20190121110823-7003.cr2

-rwx------ 1 tew tew 23777211 Jan 21 11:08 20190121110852-7004.cr2

-rwx------ 1 tew tew 25369539 Jan 21 11:09 20190121110922-7005.cr2

-rwx------ 1 tew tew 22675822 Jan 21 11:11 20190121111113-7006.cr2

-rwx------ 1 tew tew 23377077 Jan 21 11:11 20190121111119-7007.cr2

They are all pretty close in size, but there's definitely some variance, which is primarily due to compression of the raw sensor data as well as the metadata and embedded JPG preview image.