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Alann

Channels Selection -Test failure

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Affinity Photo Version 1.8.5.703

Windows 10

This is a test of the Channel Selections to isolate the blue channel and apply adjustments to just the isolated channel

When I grey out the Red, Green, and Alpha edit pencils I expect to be just looking at the Blue Channel of my selected image.
When I right click on the Blue Channel and select "Load To Pixel Selection" I expect the marching ants to be selecting ONLY all the saturated Blues in my image.
However, in the attached screenshot it can be seen that the marching ants are selecting all the saturated blues at well as the saturated Reds and Greens that are less than 50% grey, and the white alpha areas.
In addition when I select the Brightness/Contrast Ajustment layer and adjust the brightness I see the whole image getting lighter and darker.  I would expect just the Blue saturated colors to be brightened or darkened.

This same Channel Selections test of the Red and Green channels also exhibits the same issues.

See Screen Shot Attached

See Blue Channel Test .afphoto file

See Primary Colors jpeg file (selected image)

Primary Colors.jpg

screenshot.png

Blue channel test.afphoto

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Alann, you are getting the correct results, in my opinion.

When you make a Pixel Selection from the Composite Blue channel, the value (intensity of selection) of a pixel of the Pixel Selection should be (and is) equal to the value of the B component of the corresponding pixel of the document composite.

Your selection actually extends outside of the marching ants boundary. Marching ants surround regions where the selection intensity is greater than 50%, and so the ants are not a reliable indicator of the extent of a selection. The greyscale representation of the mask of your Brightness/Contrast Adjustment is showing the intensity of each pixel of the Pixel Selection from which the mask was derived and it matches the blue channel of the document composite at the moment you made the selection.

The Brightness/Contrast Adjustment doesn't only adjust the fully saturated blue of the underlying composite because its mask is allowing it to affect the entire document by some amount wherever the mask value is not zero.

 

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16 minutes ago, anon2 said:

Alann, you are getting the correct results, in my opinion.

When you make a Pixel Selection from the Composite Blue channel, the value (intensity of selection) of a pixel of the Pixel Selection should be (and is) equal to the value of the B component of the corresponding pixel of the document composite.

Your selection actually extends outside of the marching ants boundary. Marching ants surround regions where the selection intensity is greater than 50%, and so the ants are not a reliable indicator of the extent of a selection. The greyscale representation of the mask of your Brightness/Contrast Adjustment is showing the intensity of each pixel of the Pixel Selection from which the mask was derived and it matches the blue channel of the document composite at the moment you made the selection.

The Brightness/Contrast Adjustment doesn't only adjust the fully saturated blue of the underlying composite because its mask is allowing it to affect the entire document by some amount wherever the mask value is not zero.

 

According to James Ritson's video https://affinity.serif.com/en-us/tutorials/photo/desktop/video/334256548/ when I select the Blue Channel, and I apply an adjustment, it should only affect the Blue Channel information.  In James' video he applies a Gaussian Blur Filter.  When I apply the same filter to my test pixel layer the filter actually affects the Red and Green channel information and not the Blue channel information.  So, unless I am missing something, this does not seem to be working correctly.

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2 minutes ago, Alann said:

According to James Ritson's video https://affinity.serif.com/en-us/tutorials/photo/desktop/video/334256548/ when I select the Blue Channel, and I apply an adjustment, it should only affect the Blue Channel information.  In James' video he applies a Gaussian Blur Filter.  When I apply the same filter to my test pixel layer the filter actually affects the Red and Green channel information and not the Blue channel information.  So, unless I am missing something, this does not seem to be working correctly.

That's a significantly different scenario from the one of your opening post.

When I do as James did, only the blue channel gets blurred by the filter. I suspect you used the Live Gaussian Blur Filter and not the destructive Gaussian Blur Filter that was used by James.
The live filters and adjustments are not influenced by the disabling of the editability of document composite channels, whereas the destructive filters are influenced.
The blend options of a layer/object, including live filters and adjustments, lack the channel toggles found in the layer blend options of Photoshop. These toggles have been requested for Affinity, so we can only hope they are added sooner rather than later.

 

 

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12 hours ago, anon2 said:

That's a significantly different scenario from the one of your opening post.

When I do as James did, only the blue channel gets blurred by the filter. I suspect you used the Live Gaussian Blur Filter and not the destructive Gaussian Blur Filter that was used by James.
The live filters and adjustments are not influenced by the disabling of the editability of document composite channels, whereas the destructive filters are influenced.
The blend options of a layer/object, including live filters and adjustments, lack the channel toggles found in the layer blend options of Photoshop. These toggles have been requested for Affinity, so we can only hope they are added sooner rather than later.

 

 

I used Filters>Blur>Gaussian Blur, which are the same keystrokes James used in his video.

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1 hour ago, Alann said:

I used Filters>Blur>Gaussian Blur, which are the same keystrokes James used in his video.

Strange that I get James's results (only blue channel being blurred) and you don't. I'm using a Mac, though, so maybe there is a Windows-only bug.

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3 hours ago, anon2 said:

Strange that I get James's results (only blue channel being blurred) and you don't. I'm using a Mac, though, so maybe there is a Windows-only bug.

Must be a Windows problem.  Thanks for confirming it works on a MAC.  Maybe this will post will be forwarded to the Development group!

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