When cameras come out the company often states that the image processor is upgraded.

Does such an upgrade matter when one only shoots in RAW?

When shooting RAW the image is taken directly from the sensor. The processing happens off-camera on the computer.

Does the on-camera image processor process the RAW image or is it just used when the camera outputs JPEG?

If it comes into play when shooting RAW, what does it exactly do?


Short answer: Yes.

Because it isn't an "image processor", it is the camera's CPU (assuming that you don't speak about beasts like Canon 1D X which has three processors).

It matters for:

  • How many sustained Frames per Second do you have. IOW how quick it moves the images in the buffer and how quickly empties the buffer on card. This also requires processing: creating the thumbnail, writting the EXIF data, appling some image processing options which are applied to RAW - for example Highlight Tone Priority (in Canon therms, google for it - Nikon has a similar feature).

  • AF engine management. Speed, two-way communication with the lenses etc.

  • Metering management
  • digital push/pull for certain ISO values.
  • Lens corrections (Vigneting, some CA etc.)
  • Is the push/pull and the lens correction also done when shooting RAW? Jun 8 '12 at 8:01
  • Yes, sure. Push/Pull is to have ISOs 125, 160 and multiples. As you (probably) know, the camera has as native ISOs 100, 200, 400, 800, 1600, 3200... etc. The inbetween values are done digitally. For lens corrections, you can simply try with your camera (perhaps, it depends on the brand) - I know, for example that Canon applies HTP to RAW while ALO (Automatic Lighting Optimizer) applies only to JPEGs. Nikon (AFAIK) applies both to RAWs. The same could be with Lens corrections. Jun 8 '12 at 9:47
  • Peripheral - 'Regional contrast adjustment' (ALO, Dlighting, DRO ...) in RAW would be very naughty indeed as it adds nothing that cannot be done in post processing but does remove information that cannot be restored. Jun 8 '12 at 15:58
  • To be fair lens correction can be (and often is) done in post, but it is a nice perk to see how much is being cropped on-the-fly, especially if it can show it in real-time in live view mode. Some cameras also have B&W live view which can be useful for composition. I think processing power also affects frame rate of live view. Jun 10 '12 at 11:42

It shouldn't matter in terms of image quality.

But I do think that it matters in the speed at which the cameras can process the images and move them to the memory card (the processor still generates a preview, adds exif data to the file, etc). So in overall, I think it would affect the max burst rate, or at least how many pictures you can take in a row at max burst rate.


In terms of the final quality of the image you create from the RAW, it doesn't matter. Where it does matter is the after-shot review (and the histogram) since the only way to show that review is by processing the RAW data. As @Pete mentions this means it is also likely to affect the burst rate performance of the camera.

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