What is the difference between RAW images and another uncompressed format like BMP?
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The big difference with raw images is that they offer more dynamic range – the difference between the darkest value and the lightest value.
Typical image formats use 8 bits per color per pixel, so the red values can range from 0 to 255.
The actual sensor on the camera has 13, 14, or even more bits per pixel, so they have far more distinct intensities for each of the color. The RAW format stores all of that information.
If you use a program like Adobe’s lightroom, you can then choose how to map those 14 bits of red (and the other colors) to the 8 bits of the final image.
Here’s a wonderful example using an image captured by space photographer John Kraus:
[https://twitter.com/johnkrausphotos/status/1397229545074331652](https://twitter.com/johnkrausphotos/status/1397229545074331652)
The left image shows the unprocessed version. He is capturing the detail in the exhaust of the rocket, which is extremely bright, so everything else is just black in the original 8-bit image. This is a daytime launch image.
But the camera he uses recorded lot of detail in the black areas, and he is able to increase the brightness of that area of the image, and it turns out it recorded a ton of useful detail.
Working with raw images in a program like lightroom is magic.
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