Is there a demosaicing issue with RAW files?

[gordo]

I've been using Affinity Photo for awhile (in conjunction with PShop CC) but, with the Beta version I've started to try and use it to open RAW images (Sony a77ii). I've run into a bit of an issue in that Affinity seems to have a problem with demosaicing RAW images.

 

My attached example is a tight crop of an image to show the effect. On the left is the Affinity image opened and developed with its presets. On the right is the same RAW image opened with PShop. The red fingers on the Affinity version point to the artefacts - a Magenta/Green fringe on the spine of the Sargent book and the black wire. The white text on the spine of the center book is garbled colored pixels.

 

On the right is the same image using PShop's default for opening the image. No color fringing.

 

At first I thought this was some kind of chromatic aberration however on the Affinity image the Magenta/Green fringes aren't place on the same sides of the affected images. 

[TonyB]

What happens if you switch chromatic aberration on? PShop CC will switch on many settings automatically but we don't in Affinity.

[gordo]

What happens if you switch chromatic aberration on? PShop CC will switch on many settings automatically but we don't in Affinity.

 

If I switch chromatic aberration correction "on" in Affinity nothing changes. So I don't think it's chromatic aberration in the original image.

  Opening the RAW image in PShop at its default settings with chromatic aberration turned off keeps any chromatic aberrations (if present in the original shot).

  With chromatic aberration turned off in PShop the color fringing that appears in the Affinity developed image does not appear in the PShop image.

  Affinity corrects chromatic aberrations very well when they're present in the image. However this color fringing does not appear to be chromatic aberration and is not affected by turning on chromatic aberration correction in Affinity. 

[Andy Somerfield]

PS might be doing some automatic defringing - does the defringe facility in Develop help to correct the image?

 

Thanks,

 

Andy.

[Bereklauw]

I have exactly the same issues with my Fujifilm cameras. The native Serif RAW engine does a poor job. I experience the following issues:

• the Fujinon lenses are not recognised 
• the Dynamic Range settings are not recognised, the images show up way to dark
• defringing / CA does not seem to be working

Now that we have the option to choose our Apple RAW engine things are improving. Dynamic Range settings are applied and there is hardly any fringing. Still my Fujinon lenses are not recognised, which is strange because Aperture has no issues. I have enclosed screen captures to point the issues out. 
 
The screenshots show the same image: 3x Serif RAW (1 is opened up by 2 stops, to show more clearly) and 2x Apple RAW. The photo is taken with DR setting at 400%. 

[gordo]

I guess my last post/response hasn't been vetted yet?
 
Here's another example - and a new twist that I've seen before but ignored:
 
Affinity does not open RAW images in the same position as PShop. If you overlay the Affinity image on top of the PShop version and set the transparency to, say 40%, you'll see the difference in image alignment as in the attached example.

 

I've also attached another image that shows this apparent demosaicing issue. All settings in the RAW processor for both Affinity and PShop are "OFF". I've circled an area that shows the issue - Affinity on the left and PShop on the right.

 

I'd love to use Affinity as my primary editor - but this issue means I have to use a separate RAW processor.

 

 

[James Ritson]

I guess my last post/response hasn't been vetted yet?

 

Here's another example - and a new twist that I've seen before but ignored:

 

Affinity does not open RAW images in the same position as PShop. If you overlay the Affinity image on top of the PShop version and set the transparency to, say 40%, you'll see the difference in image alignment as in the attached example.

 

I've also attached another image that shows this apparent demosaicing issue. All settings in the RAW processor for both Affinity and PShop are "OFF". I've circled an area that shows the issue - Affinity on the left and PShop on the right.

 

I'd love to use Affinity as my primary editor - but this issue means I have to use a separate RAW processor.

 

Hi gordo,

 

Apologies for the bump, I've just found this thread as you linked to it from the sticked Photo Beta thread.

 

For the alignment issue, I suspect this is because using the SerifLabs engine retains a slightly higher pixel resolution than other RAW engines, therefore if you compared it to an output from Adobe Camera Raw, or indeed Apple's Core Image Raw, it wouldn't align.

 

You can see this for yourself; develop a RAW image using the SerifLabs decoder and note the pixel resolution listed in the top left. Now access the assistant settings (click the tuxedo icon on the top toolbar) and set the decoder to Apple Core Image RAW. Cancel the development and open the same raw file again. This time you should note a different, slightly lower pixel resolution.

 

 

As for the artefact issues, the most recent screenshot definitely looks like something I'd tackle with defringing; try a very low edge brightness threshold (but not at 0% as it'll have no effect then) and a high tolerance, then check "Also remove complementary hue". Set your colour correctly on the hue slider and this will usually remove most of the fringing in the image if not all.

 

As Tony mentioned earlier in the thread, ACR does a lot of automatic processing, some of which you can't disable. It's a divisive approach, perhaps, but Photo's Develop persona lets the user determine everything manually, down to noise reduction and lens artefact removal.

 

If you were to use the Apple Core Image RAW decoder, that includes a few automatic adjustments including noise removal and lens distortion. Have you given that a try to see if it improves the issue?

 

Hope that helps!