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marmite

Convert colour to transparency

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Hi Folks

 

Is there a way in either Photo or Designer to convert a solid colour in an existing image (let's say a png for the sake of argument) and make it transparent?

 

I've found many existing posts about transparency. Some relate to creating an image with a transparent background which isn't applicable here. Some relate to existing images but I don't believe it's quite the same scenario; nothing I can get to work anyway.

 

So effectively I'm looking for the equivalent of GIMP's 'Color to Alpha' function. I've had to install GIMP just for this purpose; I'm struggling to believe there isn't a way of doing it in either AD or AP but I'm not that au fait with image programs of this complexity.

 

Thanks

 

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Hi Marmite,

 

Welcome to the Forums :)

 

To select a colour from a photo and make it transparent you can do the following:

 

1. Go to Select and then Select Sampled Colour.

2. Click the colour you want and refine the selection until you are happy with it.

3. At the bottom right  of the App there is the Channels Tab inside this tab is the Pixel Selection Channel.

4. Right click this Channel and click Invert then click Create Spare Channel.

5. You will now see a Spare Channel below the Pixel Selection Channel.

6. Right click the Spare Channel and choose Load To Background Alpha.

 

This should then make the Colour Selection transparent :)

 

C

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Hi Callum

 

Thanks for the welcome.

 

And for the solution ... that works nicely. Although if I could understand exactly what I'd done I'd be laughing  :wacko:

 

Cheers  :)

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This didn't work for me.

I have flat pasted a selection from one layer into another that has a transparent background.
This gives me almost the selection I want to work with but to refine it I have used select by sample colour to select a range of pixels that I wish to convert to background transparency.
In GIMP with such a selection I would simply delete the selected parts of that layer making the chosen pixels part of the transparent background.

I followed the procedure outlined above but it just turned my background black and the selected colour remained unchanged.
I'm sorry if this seems to "hijack" the original question but the topic title is absolutely apt as I wish to make the colour I now have selected just a part of the transparent background on this layer.

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Thanks - first time I tried it didn't appear to work but following your advice it did , just was noticeably slow and maybe I was too hasty to deselect the first time.

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Try Select> Select Sampled Color> choose the color you want to select then set your tolerance and apply, then you clear the selected area.

If you need it to select more than one color you can save one as a selection channel and do the other color then add the selections together.

 

I've also found that making your image black and white can enhance certain selections too, you can make a black and white later of the image just for selection purposes then go back to your colored layer.

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On 9/11/2015 at 4:18 AM, Callum said:

Hi Marmite,

 

Welcome to the Forums :)

 

To select a colour from a photo and make it transparent you can do the following:

 

1. Go to Select and then Select Sampled Colour.

2. Click the colour you want and refine the selection until you are happy with it.

3. At the bottom right  of the App there is the Channels Tab inside this tab is the Pixel Selection Channel.

4. Right click this Channel and click Invert then click Create Spare Channel.

5. You will now see a Spare Channel below the Pixel Selection Channel.

6. Right click the Spare Channel and choose Load To Background Alpha.

 

This should then make the Colour Selection transparent :)

 

C

Callum,

Thank you for this procedure, but it no longer appears to work in the current version of the Affinity Photo software.  I just tried it and I could do all the steps except for step 6.  When you right click on the spare channel that you just created, there is no option to "Load to Background Alpha".  Instead there are the options to "Rename", "Delete", "Load to Pixel Selection", "Add to Pixel Selection", "Subtract from Pixel Selection", and "Intersect with Pixel Selection", none of which seems like the correct option for this task.  

For reference, I'm using Affinity Photo v1.6.11.  Not sure when the change occurred, but unfortunately this solution no longer seems to work. Any other suggestions from anyone out there?

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18 hours ago, >|< said:

Ignore the contortions with channels and just press the delete key to make the selected pixels become transparent.

Oh! Much better.  So just for everyone else out there, just do steps 1, 2, and then hit delete to make the sampled color become transparent.

 

Thank you!

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