Photoshop needs "Color to Alpha" button

[dolldivine]

I was just chatting with a group of other artists about the need to convert a color into transparency sometimes, and we've all needed such a function, then somebody said that in GIMP there's just a simple button for it, "Color to Alpha."  It does exactly what we need and very easily.  In Photshop this is possible but very cumbersome, having to use the channels to make a selection, then apply a mask.

Googling leads to 10 year old articles and people recommending plugins.  But yeah, I'd just like to suggest this as an official feature request.

You know how in Photoshop you can use Replace Color?  And you can pick a color, and vary the fuzziness of the selection, then change the color to something else?  It would be just like that I imagine, but instead of changing the color, you increase the opacity of those pixels.

[unique_person4993]

Okay I'm a bit confused, when I commented on this yesterday there was a separate thread as linked by the original author, but now it's just redirecting me to this one and showing my comment here? It seems the two got merged? Huh. As long as it still counts as a feedback/suggestion thread at least.

Anyway, yes thanks a ton for that! I'll need to set that up, point still stands though that this would be super helpful to have as an included feature instead of having to set up a fancy action for it... Especially if this only works for black and white, I know in the past I had to use GIMP's colour to alpha for some other colours as well, white is just the most common.

[Stephen Marsh]

Yes, it appears that two separate topics were merged.

This is standard practice for ideas or bug topics, as Adobe track the votes. Although one can vote on a regular discussion, those are not tracked by Adobe, so it's rare that duplicates are merged.

I do note that this topic is still marked as a discussion and not an idea/feature request.

[Stephen Marsh]

I'm not sure what happened to the feature request idea topic, I'm sure that it has 12 votes!

Could a moderator please change this topic to an idea if that was changed when merging topics?

[unique_person4993]

It looks like someone had previously told the original author to make another post as a feedback post, which I why I thought it was weird that it was merged into this one, BUT looking at the URL it's now in ideas rather than discussion, and it no longer has "solved" in the title, so I think they just thought this post was more informative and made it the main post. Probably a good idea! (It did lose a couple of upvotes though, one of the author's replies on the previous page has the content from the other thread with 12 upvotes, so I think that's where those went.)

@Stephen Marsh The action you gave me worked great! ...Except, this logo appearently uses a very dark gray rather than black, so it ended up making the letters semi-transparent. Which is how it's intended to work, but not exactly what I needed in this case. GIMP has an "Opacity Threshold" that can be used to keep colours that only have a bit of the colour you're removing from becoming semi-transparent with some tweaking, thankfully, which is a nice option.

I think this is another point towards why Photoshop should impliment this feature! (Especially because GIMP tried to export my image as a half a gigabyte file...?? No idea why. Not super fond of that program to be honest.)

[M-H]

Photoshop already has "selection to alpha" button and it also has Color Range selection so basically 2 step solution to get any colour transparent/masked. If thats too much clicking you can record both as action and turn dialog on for the first step:

Takes seconds to do either way so I wouldnt be expecting Adobe developers to be jumping on it to "reinvent the wheel"

[Stephen Marsh]

Photoshop already has "selection to alpha" button and it also has Color Range selection so basically 2 step solution to get any colour transparent/masked. If thats too much clicking you can record both as action and turn dialog on for the first step:

Takes seconds to do either way so I wouldnt be expecting Adobe developers to be jumping on it to "reinvent the wheel"

By @M-H 

If you read the first half of the topic, you will see that what the Color to Alpha function does in Gimp and Krita isn't the same.

[M-H]

Of course results from 2 different pieces of software using different algorythms and with different user settings (100 threshold vs 200 fuzziness) are going to be different. Im pretty sure just gimp only could give 100s of slightly different results, what is your point? Author in the org post says she needs just a single button for it because in "Photshop this is possible but very cumbersome, having to use the channels to make a selection, then apply a mask." which isnt true

[unique_person4993]

@M-H Yes, two different actions in two different software DO produce completely different results, because they are two different functions that are not directly comparable. Hence why we're requesting that Photoshop add that function. 

Here's an example of the "Color Range" and making the selection be the alpha channel in Photoshop, vs how it looks when using the "Color to Alpha" feature in GIMP. The black text was on a nice lavender background as shown by the dot next to it, and the red text was on a horrendous neon green background. 

You can see that in the GIMP Color to Alpha example the lavender and green were completely masked out, with those pixels inbetween the colours becoming instead a semi-trasparent pixel that doesn't have any of the masked out colour in it. 

(Yes I'm a real graphic designer, I made the font be Comic Sans to be a little silly with it all.)

[M-H]

@unique_person4993 thanks for torough explanation, I get it now! Personally, I dont think I've ever actually needed that function for my work but now for sure I wouldnt mind that in PS! Any ideas on rgb math behind that function in GIMP? Frankly im struggling now to get even similar results in PS🤦‍:male_sign:I was hoping mix of masking and blend if would get at least in ballpark but its not the case...

[unique_person4993]

@M-H No problem! I'm glad my example was helpful, especially since the discussion earlier in the thread was talking about a picture on a white background, which there's technically a workaround for. 

It's definitely a bit of a niche use case! I don't need it often but there's been a few times it would have been super helpful, and it just feels like something Photoshop should be able to do, since it's a feature that is possible in other programs? And is pretty similar to some existing functions Photoshop can do. 

I'm not very savvy on the technical side of things, but it seems like there's a discussion here about how GIMP's Color to Alpha feature calculates things, though a lot of the conversation is rather old, with the thread being from 13 years ago... (Though this thread also let me know that a certain online photo editor has the feature as well! That may be my fallback for this in the future since GIMP and I seem to not get along very well.)

https://stackoverflow.com/questions/9280902/what-algorithm-is-behind-the-gimps-color-to-alpha-featur...

[Stephen Marsh]

@unique_person4993 - There's also Krita which isn't a web app.