iMac 5k 100% zoom view

Submitted by mactwin on Sat, 07/29/2017 - 01:44
Forums: 
General discussion

Hi, after several tests I have not been able to find the way to preview 100% of raw files, with internal preview not full resolution (I've also clearly set preferences to ignore the internal preview)
The preview generated by FRV appears less definite than what it should compared to the view of a jpeg in full resolution or the same raw seen at 100% with PS.
The problem seems a retina compatibility, because if I put OFF "use logical pixel for zoom calculation" the 100% is like the PS 100% view but smoother (and is not enough zoom to see detail on retina) while set it ON I can get the optimal 100% that is the same of PS at 200% ...but it was very very smooth if compared to PS.

LibRaw

Sat, 07/29/2017 - 09:25

Dear Sir:

You are comparing fully processed JPEGs, it sharpening applied during the processing, to fast demosaicking in FastRawViewer.

During final raw convertion (in-camera or using a converter on a computer) sharpening is applied behind the scenes automatically (which, in our mind, is not an option for evaluating raw images), and also converters use slower demosaicking.

 

To help with the issue, In FastRawViewer we have:

 

Focus Peaking, 'E' and 'D' buttons on the bottom bar or through a shortcut, assigned to 'P' key by default.

• 'E" is for High contrast edges – enables the outlines for contrasty details using color contouring. Edges display color sets the color for the contours.

• 'D' is for Fine details – enables the outlines for the areas with plenty of smaller sharp details using color contouring. Details display color sets the color for the contours.

• Focus Peaking layer opacity in Preferences, GPU Processing – controls the fading of the main image for the Focus Peaking contours to be visible better. 

 

Screen Sharpening, 'USM' button on the bottom bar or through a shortcut, assigned to 'S' key by default. The settings for Screen Sharpening are in Preferences - Image Display - On-screen Sharpening; 2 presets.

• Preset 1/Mode:

• Always on – sharpening for display is always on

• Button/Shortcut – turns on when the button is pressed.

• Preset 2/Enabled – allows one to use a second group of parameters for sharpening, thus cycling will be between Off-Preset1-Preset2 or Off-Preset1.

• Radius – the radius the Unsharp Mask filter, which closely correlates to the Radius parameter in Adobe Photoshop USM settings.

• Amount – the strength of the sharpening, same as Amount Photoshop USM amount.

• Sharpen RAW files only – if this setting is on, the sharpening for display will affect RAW files only. 

 

More computationally intensive demosaicking, Preferences - GPU Processing - Image Resampling Method drop-down.

• No resampling – for large zoom factors, the image will look as if it is constituted of small square tiles. The fastest method.

• Bilinear resampling – pretty fast, mid-quality method

• Bicubic resampling – high-quality method, can be slow, a relatively fast vast video card is recommended.

mactwin

Sat, 07/29/2017 - 09:57

Hi first of all thanks for fast response, yes I understand the process use by the application and all the options, I just try to understand if there were an option to enable FRV to create a better preview with high resolution (and why not the minimum denoise like Camera Raw standard) with obviously cost of speed.
Maybe it will be a good feature for next version, thats because on some computer like the new fastest (i7 4ghz and R9 or better card) maybe the power can be enough to reach a better quality reamain enough fast to get the right process (like now that is maybe the best app).
If I think to acutal preview generation like a 50% of real pixel (I mean size of rendered image in pixel*pixel), it will be great to have some option like 66%, 75%, 88%, 100%, and another opion to enable a little noise (1 or more level).
Thanks for your support! 

Jason (not verified)

Wed, 08/09/2017 - 14:06

I'm not sure if this is exactly the same issue, but I'm on a 4k monitor and I'm getting this: http://imgur.com/a/6QBa0
I was wondering why my shots were so unsharp for a while before finally opening them in ACR. You can see the sharpening is turned off in ACR. It seems like FRV is resampling even at 100%, but I thought that is only for zooming in or out.

LibRaw

Wed, 08/09/2017 - 15:19

Raw converters employ default sharpening that can't be switched off, it is the nature of the demosaicking used in raw converters. You can switch off user-level sharpening only.

To check sharpness in FastRawViewer, please use FastRawViewer features such as sharpening for display, focus peaking, JPEG previews. 

Jason (not verified)

Wed, 08/09/2017 - 16:51

How come when I turn off resampling, I get aliasing (jaggies), which is a clear resizing artifact? http://imgur.com/a/eEvjs
I know sharpening algorthms. There is no sharpening that can make images go from very blurry or jaggy to perfectly sharp in ACR without introducing haloing or artifacts. FRV is clearly not displaying all the raw data at 100% zoom.
Maybe it's dumping some data to optimize speed, I don't know. But the difference between ACR and FRV cannot be explained by saying that ACR is doing secret sharpening.
This isn't some small issue--It's like someone smeared vaseline on the screen. If this is only a problem on 4k monitors, maybe you need an option to accommodate that. Do you test on 4k monitors?

LibRaw

Wed, 08/09/2017 - 17:15

Dear Sir:

You are trying to apply your practical experience with sharpening in Photoshop to programming demosaicking. That does not work. Demosaicking algorithms used in raw converters do not use the sharpening you are familiar with. Often they do not even use a separate step for sharpening. FastRawViewer does not "dump" any data, we simply process it very fast, the demosaicking sharpeness/denoising vs. speed slider being moved towards the "speed" end. Instead for sharpness evaluation we offer the tools I listed above.

Jason (not verified)

Wed, 08/09/2017 - 17:30

So where is the aliasing comming from? Are you suggesting that image captured by the camera is just naturally filled with jaggy edges?

LibRaw

Wed, 08/09/2017 - 18:44

Dear Sir:

Raw data is naturally aliased because of sampling, sampling overlays a raster. That is why many cameras have anti-aliasing filters. That is why 'super-sharp' demosaicking algorithms are prone to labyrinth-type ("zipper") artifacts. Here is a couple of articles that may interest you: Sampling theorem and Aliasing.

Jason (not verified)

Sat, 08/12/2017 - 19:51

Do you have plans to implement an accurate demosaicing algorthm (for fast machines/4k monitors) so professionals who need to check sharpness and focus can use this software?
I'm not going to complain about the few dollars I spent on this. It's easily worth that. But I am now looking for a raw viewer that does what I need, even if I have to spend a lot more.

LibRaw

Sat, 08/12/2017 - 20:12

Dear Sir:

Fast high quality demosaicking is pretty high on our ToDo list.

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