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Colour in gradient black to opacity


dmstraker

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  1. Draw a rectangle shape.
  2. Draw a gradient, black to red, across it.
  3. Gradient colour, select red end and reduce opacity to zero.

You can still see red in the gradient, even though the red opacity is zero. 

Fix is to change red node to black (or whatever the other node colour is.

Dave Straker

Cameras: Sony A7R2, RX100V

Computers: Win10: Chillblast i9 Custom + Philips 40in 4K & Benq 23in; Surface Pro 4 i5; iPad Pro 11"

Favourite word: Aha. For me and for others.

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9 minutes ago, dmstraker said:
  1. Draw a rectangle shape.
  2. Draw a gradient, black to red, across it.
  3. Gradient colour, select red end and reduce opacity to zero.

You can still see red in the gradient, even though the red opacity is zero. 

Fix is to change red node to black (or whatever the other node colour is.

Why do you rate this as bug?
the gradient will create a mix of:

black/ 100% alpha

via black 50% alpha,  red 50% alpha

to black 0% / red 0%

so for me it is correct that you see a mix of black and red with reduced opacity at the middle of the gradient.

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.

 

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3 minutes ago, NotMyFault said:

Why do you rate this as bug?
the gradient will create a mix of:

black/ 100% alpha

via black 50% alpha,  red 50% alpha

to black 0% / red 0%

so for me it is correct that you see a mix of black and red with reduced opacity at the middle of the gradient.

This makes sense. 

And yet by setting the opacity to zero, you can also argue that the gradient is from black to no colour.

Hmm.

Dave Straker

Cameras: Sony A7R2, RX100V

Computers: Win10: Chillblast i9 Custom + Philips 40in 4K & Benq 23in; Surface Pro 4 i5; iPad Pro 11"

Favourite word: Aha. For me and for others.

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The gradient just creates a linear share of the individual color channels and alpha. For me this makes sense.

If we take your interpretation, it would be impossible to create gradients over alpha channel.

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.

 

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Understood and accepted.

There's also the psychology of perception to consider. Looking at the red-with-zero-alpha node in the gradient panel or on screen, it appears to be transparent node. Yes, showing it as 'red with zero alpha' could be tricky. But cognition is often based on simple visual cues more than an examination of further panel data. And so (as with me), it is easy to assume that what is seen is all there is.

This is what, in my development/QA/HF days we would have designated a 'usability defect'. There is clear logic in why it is what it is, but nevertheless it is experienced as a confusing difficulty.

What the solution is here, I don't know. Nor is it a hill on which I plan to expire. I'll leave it to the good people in Serif to figure what to do about it.

Dave Straker

Cameras: Sony A7R2, RX100V

Computers: Win10: Chillblast i9 Custom + Philips 40in 4K & Benq 23in; Surface Pro 4 i5; iPad Pro 11"

Favourite word: Aha. For me and for others.

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1 hour ago, dmstraker said:

I'll leave it to the good people in Serif to figure what to do about it.

Is V2 behaving any differently than V1?

 

-- Walt
Designer, Photo, and Publisher V1 and V2 at latest retail and beta releases
PC:
    Desktop:  Windows 11 Pro, version 23H2, 64GB memory, AMD Ryzen 9 5900 12-Core @ 3.00 GHz, NVIDIA GeForce RTX 3090 

    Laptop:  Windows 11 Pro, version 23H2, 32GB memory, Intel Core i7-10750H @ 2.60GHz, Intel UHD Graphics Comet Lake GT2 and NVIDIA GeForce RTX 3070 Laptop GPU.
iPad:  iPad Pro M1, 12.9": iPadOS 17.4.1, Apple Pencil 2, Magic Keyboard 
Mac:  2023 M2 MacBook Air 15", 16GB memory, macOS Sonoma 14.4.1

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One last note, and perhaps something that Serif can address.

In the Gradient colour panel, when you reduce opacity, the colour as displayed decreases to grey. But if the colour is still being used (as it is) in creating the gradient, then perhaps the colour should remain, hence giving some indication that you are going to still get the colour within the gradient. 

Image attached.

gradient bug.jpg

Dave Straker

Cameras: Sony A7R2, RX100V

Computers: Win10: Chillblast i9 Custom + Philips 40in 4K & Benq 23in; Surface Pro 4 i5; iPad Pro 11"

Favourite word: Aha. For me and for others.

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47 minutes ago, walt.farrell said:

Is V2 behaving any differently than V1?

 

No, but that doesn't stop it being a usability defect, as per notes above.

Dave Straker

Cameras: Sony A7R2, RX100V

Computers: Win10: Chillblast i9 Custom + Philips 40in 4K & Benq 23in; Surface Pro 4 i5; iPad Pro 11"

Favourite word: Aha. For me and for others.

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15 minutes ago, dmstraker said:

No, but that doesn't stop it being a usability defect, as per notes above.

Sorry, but I don't agree that it's a usability defect.

19 minutes ago, dmstraker said:

In the Gradient colour panel, when you reduce opacity, the colour as displayed decreases to grey. But if the colour is still being used (as it is) in creating the gradient, then perhaps the colour should remain,

It can't. It has 0 opacity, so you can only see the background color of the dialog itself.

You see the actual color in the gradient color bar at the top of the dialog.

-- Walt
Designer, Photo, and Publisher V1 and V2 at latest retail and beta releases
PC:
    Desktop:  Windows 11 Pro, version 23H2, 64GB memory, AMD Ryzen 9 5900 12-Core @ 3.00 GHz, NVIDIA GeForce RTX 3090 

    Laptop:  Windows 11 Pro, version 23H2, 32GB memory, Intel Core i7-10750H @ 2.60GHz, Intel UHD Graphics Comet Lake GT2 and NVIDIA GeForce RTX 3070 Laptop GPU.
iPad:  iPad Pro M1, 12.9": iPadOS 17.4.1, Apple Pencil 2, Magic Keyboard 
Mac:  2023 M2 MacBook Air 15", 16GB memory, macOS Sonoma 14.4.1

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7 hours ago, dmstraker said:

And yet by setting the opacity to zero, you can also argue that the gradient is from black to no colour.

That is faulty logic, the gradient goes from black to red regardless of opacity. What happens with a gradient with the last stop with an opacity of 10%? should the gradient be shifted over so only the final 5 or 10% of the distance has any red instead of the original 50%?

Mac Pro (Late 2013) Mac OS 12.7.4 
Affinity Designer 2.4.1 | Affinity Photo 2.4.1 | Affinity Publisher 2.4.1 | Beta versions as they appear.

I have never mastered color management, period, so I cannot help with that.

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