A7R2 - Firmware update available (14-bit uncompressed RAW)

[ShooterSteve]

Again, at 800ISO. Compressed on the right this time. This is with Exposure at +1.75 and shadows +100 though, which is a setting I would try to avoid. Quite underexposed and normally I wouldn't push shots this far, but it's a long way from 6 stops underexposed and I'm still seeing a difference in low frequency noise and color casts in the shadows.

View attachment 113352

The color shift is dramatic. I wonder what could explain that? All the explanations with the lossy compression were dealing with highlight issues etc. Kind of scary.

 

[Wayne Fox]

It would be interesting to see if this minor difference will be visible in a print. I suspect, not.

Pretty large color shift. Even without the exaggerated processing seems it would be noticeable.

 

[davidstock]

This post summarizes where we stand today with the issue: http://www.dpreview.com/forums/post/56653457

As is shown, the strongest compression effect is blocky pixilation artifacts along high contrast edges. However, compression also seems to cause some noise and color artifacts in broader shadow areas.

This difference in the shadows has also been confirmed by users of the online KARWY tool, which was developed to fix artifacts in compressed Sony files (after the fact). http://www.dpreview.com/forums/post/56535255 The tool itself is slow, but examples from using it show that reverse engineering the lossy compression can reduce shadow noise.

--d

 

[pegelli]

Maybe a stupid question, but were the temp and tint sliders in the exact same position for these comparisons?

 

[dandrewk]

To me, the "color shift" is all in the dark object on the left side of the image. This looks like increased chromatic aberration in the compressed file. Without having access to the RAW file, I'd guess that the CA is easily correctable.

Regardless, I can't remember an instance where I've ever had to push small shadow more than a stop or two. If the shot is severely underexposed, it gets rejected.

 

[dandrewk]

I'd prefer to have the comparison without JPG included. I see no reason to embed a JPG into a raw file when all the software options we use for processing has the capability to create a JPG for its own use.

The file I used had about 25% sky and the rest was fine detail trees and bushes. I selected it because it seems about average for detail.

All RAW files have a small, embedded JPG. It's what you see when you review the image with your camera.

 

[Wayne Fox]

To me, the "color shift" is all in the dark object on the left side of the image. This looks like increased chromatic aberration in the compressed file. Without having access to the RAW file, I'd guess that the CA is easily correctable.

Regardless, I can't remember an instance where I've ever had to push small shadow more than a stop or two. If the shot is severely underexposed, it gets rejected.

Interesting. I’m not really seeing it as CA at all, more like a colorcast that increases as the densities get darker. I’ve struggled with some of my sony files for quite some time with what I’ve called“crossover”, trying to get neutral colors in the entire image without some highlights looking green vs some shadows looking magenta, something I don’t see with my Phase gear.

I’ll be interested to test the new lossless raw when I get some time to see if it helps.

 

[bdp]

Maybe a stupid question, but were the temp and tint sliders in the exact same position for these comparisons?

Yes, they were. It's not a universal color shift, just patchy blotches of magenta in pushed shadows.

Wayne I'm sure you'll see a difference if you noticed this green/magenta inbalance previously. I'd be interested to see if you can notice a difference with uncompressed raws.

 

[dandrewk]

Interesting. I’m not really seeing it as CA at all, more like a colorcast that increases as the densities get darker. I’ve struggled with some of my sony files for quite some time with what I’ve called“crossover”, trying to get neutral colors in the entire image without some highlights looking green vs some shadows looking magenta, something I don’t see with my Phase gear.

I’ll be interested to test the new lossless raw when I get some time to see if it helps.

Agreed. It's hard to really know the issue without the original RAW file.

Also keep in mind there are RAW converters and there are RAW converters. I'd love to put this RAW file through DxO's Prime NR.