Useful to be able to switch from 32 MP to (say) 8 MP RAW?

Started Nov 9, 2013 | Discussions thread
turnstyle
Senior MemberPosts: 1,633
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Re: Will actually be TIFF's, but still useful
In reply to John Sheehy, Nov 11, 2013

John Sheehy wrote:

turnstyle wrote:

Grevture wrote:

turnstyle wrote:

sroute wrote:

Respectfully, what's the point? Once you do that, you might as well be shooting JPG.

If you want a lower resolution file, then by definition you aren't concerned about absolute fidelity. In that case, set up the in-camera JPG processing to your taste, and shoot away. You'll have smaller files and can still tweak them to some degree.

Problem solved, IMO.

Is it really so hard to understand that somebody might want the benefits of RAW -- ability to adjust WB, dynamics, etc. -- but not also need a 36MP file every time?

You can actually use a high quality jpeg for that, the difference in post processing capabilities between a high quality jpeg and a reduced size (so called) raw file will be surprisingly small. Now, I agree it can add a little usefulness if we did not have to depend on destructive jpeg compression schemes to get smaller files, but just keep in mind the difference is not that big.

Sure, sometimes I want all the resolution I can get. But there are plenty of times I know I won't need so much resolution, but I still want full flexibility in PP.

The problem is, once you do reduce the dimensions of the image, some of that flexibility in PP is gone, no matter how you go about doing the size reduction. Once the demosaicing is done - and you have to do that to able to reduce the dimensions - you have reduced your PP flexibility. For full flexibility - use the full file. With reduced file, you get reduced flexibility. It's just how it works.

This is very probably the biggest reason Sony has not bothered to offer reduced size 'raw' files, because they feel it offers very small real life advantages to using the high quality jpeg settings.

My question was based on the assumption the camera could technically generate a smaller RAW file -- perhaps by treating groups of four pixels as one larger pixel when shooting -- or by averaging them after the shot.

I'm kind of surprised if that's not possible.

Think about the pattern of color filters:

R G R G R G R G

G B G B G B G B

R G R G R G R G

G B G B G B G B

Now, how are you going to group 4 pixels together? If you just work within each 2x2 tile, you only halve green information and don't change red and blue at all, but cause color shifts because the original reds and blues are not centered in the tiles.

If you group the individual color channels into 2x2 tiles to become one pixel, the centers of all these tiles need to full resolution to be properly placed.

The only way you can create a slightly smaller (50%) RAW image is to interpolate the whole thing first in firmware, and the only way you can really save storage space on a "per-resulting-pixel" basis is by losing color detail beyond what you're downsampling or binning to. You have to go beyond 50%, down to much smaller sizes before you save MB and get quality "pixels" as a result.

This is all doable in the RAW color space, of course, it just isn't done by manufacturers. Canon has mRAW and sRAW, but those are lossy in more than just resolution; they are in the color space usually used in JPEGs, and require conversion back from it to RGB.

Thank you kindly for taking the time to share that.

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