Are RAW files from the same camera always the same size?
Asked 1/22/2019
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I’m trying to estimate processing load by counting how many images are waiting in a queue. That only works well if each image from a given camera is roughly the same amount of data. With JPEG I know file size changes because of compression, but what about RAW files from the same camera model? Are RAW images always the same size, or can they vary depending on the scene?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
7y ago
2 Answers
27
Many 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).
Originally by user15871. Source · Licensed CC BY-SA 4.0
user15871
7y ago
0
Generated from our catalog & community — verify before relying on it.
Usually not. RAW files from the same camera often vary in size.
If a camera wrote completely uncompressed sensor data, each RAW file would be nearly the same size at a given resolution and bit depth. But many cameras use lossless compression for RAW, so file size depends on image content.
Scenes with lots of fine detail, tonal variation, color variation, or visible noise tend to produce larger RAW files. Simpler, more uniform scenes tend to compress better and produce smaller files.
So for load balancing, assuming every RAW file is identical in size is not reliable. They may be similar on average, but there will be variation from shot to shot. One example given for a 20 MP camera showed a noticeable spread in RAW file sizes around the average.
If you need a better estimate of processing load, use actual file size in bytes or expected processing time rather than just image count.
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