Jump to content

Scope panel, intensity waveform


Recommended Posts

Hi,

there is a mismatch between specification and implementation of scope panel and intensity waveform (and others like RGB Parade).

According to help:

Available charts

  • Intensity Waveform—displays a scatter plot of the luminance values of pixels in an image. The X axis gives the horizontal location of the pixel while the Y axis provides its luminance value.

Observed:

For pixels with black, intensity (luminance) is shown as thick line at 100%. Expected: 0%

2FB2E26D-68D5-41A8-A35D-A5B4AE490CF1.thumb.png.e9fdf88fe7c3f2e57fb18051daec961b.png

Screenshot is from iPad, same issue on Desktop.

 

intensity waveform.afphoto

Mac mini M1 A2348 | Windows 10 - AMD Ryzen 9 5900x - 32 GB RAM - Nvidia GTX 1080

LG34WK950U-W, calibrated to DCI-P3 with LG Calibration Studio / Spider 5

iPad Air Gen 5 (2022) A2589

Special interest into procedural texture filter, edit alpha channel, RGB/16 and RGB/32 color formats, stacking, finding root causes for misbehaving files, finding creative solutions for unsolvable tasks, finding bugs in Apps.

My posts focus on technical aspects and leave out most of social grease like „maybe“, „in my opinion“, „I might be wrong“ etc. just add copy/paste all these softeners from this signature to make reading more comfortable for you. Otherwise I’m a fine person which respects you and everyone and wants to be respected.

 

Link to comment
Share on other sites

That’s actually very interesting! And what’s even more interesting, that there’s a little bug in the Color Picker that causes this problem. 

If you move sampler dot to the very black corner you’ll get H:0 S:100 L:0. I think it’s wrong. And the very black corner should actually be H:0 S:0 L:0

1154075941_ScreenShot2021-12-20at13_13_01.png.e4c34a674ac4c6e4ff351f146c29fa00.png

If you’ll move it tiny bit down from that, you’ll get H:0 S:0 L:0. Why S value getting changed from 0 to 100 here?

322333123_ScreenShot2021-12-20at13_13_44.png.244a2b412d8007ff38d043e4ddd137f2.png

Link to comment
Share on other sites

The color sampling issue could be caused by the forced dithering of gradients. It leads to kind of colored noise added to the gradient, and if the picker is set to show values in percent, it could be rounded to HSL 0, 100, 0, in reality RGB 1,0,0 which looks almost black but is actually 100% saturated darkest possible red.

Use Info panel or color panel, set to rgb sliders, set to 8bit, to see the correct color value.

So this is unrelated to the issue I raised in this thread.

Mac mini M1 A2348 | Windows 10 - AMD Ryzen 9 5900x - 32 GB RAM - Nvidia GTX 1080

LG34WK950U-W, calibrated to DCI-P3 with LG Calibration Studio / Spider 5

iPad Air Gen 5 (2022) A2589

Special interest into procedural texture filter, edit alpha channel, RGB/16 and RGB/32 color formats, stacking, finding root causes for misbehaving files, finding creative solutions for unsolvable tasks, finding bugs in Apps.

My posts focus on technical aspects and leave out most of social grease like „maybe“, „in my opinion“, „I might be wrong“ etc. just add copy/paste all these softeners from this signature to make reading more comfortable for you. Otherwise I’m a fine person which respects you and everyone and wants to be respected.

 

Link to comment
Share on other sites

Not on my Windows PC.

Whatever method i use:

  • Fill layer with color set to RGB 0,0,0 or to HSL 0,0,0 or color wheel
  • Procedural texture filter with RGB=0 and A=1
  • Channel mixer with RGB=0 and ALPHA=1

The scope gets to 100% for all pixels who are totally fully black.

 

The scope panel updates without undue delay, so i can always see the line jump from almost 0 to 100 when i move the sliders.

Mac mini M1 A2348 | Windows 10 - AMD Ryzen 9 5900x - 32 GB RAM - Nvidia GTX 1080

LG34WK950U-W, calibrated to DCI-P3 with LG Calibration Studio / Spider 5

iPad Air Gen 5 (2022) A2589

Special interest into procedural texture filter, edit alpha channel, RGB/16 and RGB/32 color formats, stacking, finding root causes for misbehaving files, finding creative solutions for unsolvable tasks, finding bugs in Apps.

My posts focus on technical aspects and leave out most of social grease like „maybe“, „in my opinion“, „I might be wrong“ etc. just add copy/paste all these softeners from this signature to make reading more comfortable for you. Otherwise I’m a fine person which respects you and everyone and wants to be respected.

 

Link to comment
Share on other sites

Yes, platform depended bug

 

In my view the MacOS behavior is wrong too. H 0 L 0 should be intensity 0 (and not 100%) no matter what value S shows.

Mac mini M1 A2348 | Windows 10 - AMD Ryzen 9 5900x - 32 GB RAM - Nvidia GTX 1080

LG34WK950U-W, calibrated to DCI-P3 with LG Calibration Studio / Spider 5

iPad Air Gen 5 (2022) A2589

Special interest into procedural texture filter, edit alpha channel, RGB/16 and RGB/32 color formats, stacking, finding root causes for misbehaving files, finding creative solutions for unsolvable tasks, finding bugs in Apps.

My posts focus on technical aspects and leave out most of social grease like „maybe“, „in my opinion“, „I might be wrong“ etc. just add copy/paste all these softeners from this signature to make reading more comfortable for you. Otherwise I’m a fine person which respects you and everyone and wants to be respected.

 

Link to comment
Share on other sites

3 minutes ago, NotMyFault said:

In my view the MacOS behavior is wrong too. H 0 L 0 should be intensity 0 (and not 100%) no matter what value S shows.

Absolutely! If L equals to 0 in both cases, there’s no influence of S can make on how Scope level is calculated for this area.

Link to comment
Share on other sites

  • 3 weeks later...
  • 2 months later...

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...

Important Information

Terms of Use | Privacy Policy | Guidelines | We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.