Convert photo to specific indexed palette?

[perihelion74]

Hi!

Guess this is a stupid question but I've tried figuring it out on my own but must be missing something here. I have a photo and I want to convert it to a set palette of just 16 colors. Eh... How do I do it? Anyone?

Cheerz!
/M

[walt.farrell]

For a PNG export, look at the More... dialog, and try something like this:
 

[eobet]

I'm also looking for this info. The above answer is not sufficient because it's not a specific indexed palette (it's "automatic", ie outside of your specific control).

Here it's described how to save a palette from an image document, but you can't use that palette to convert a document to it?

[walt.farrell]

12 minutes ago, eobet said:

but you can't use that palette to convert a document to it?

Correct, as far as I can see.

Though you can specify Custom in the Export dialog, there does not seem to be any way of choosing a specific palette in that case.

This is logged as a bug: https://forum.affinity.serif.com/index.php?/search/&tags=AFD-2432

[jmwellborn]

1 hour ago, eobet said:

I'm also looking for this info. The above answer is not sufficient because it's not a specific indexed palette (it's "automatic", ie outside of your specific control).

Here it's described how to save a palette from an image document, but you can't use that palette to convert a document to it?

If I understand your issue correctly, here is a way to create your own palette with the colours you want, rather than the automatic ones created when using Create Palette from Image. It is definitely fiddly, but it works.

1.  From the Swatches panel, hamburger menu, choose Create Palette from Image.  Then import your image document that has the colours you want.
2. When the image appears on your canvas, move the slider to choose 3 colours only.  Choose Application palette, because you must be able to find it in the Swatches panel to use for the next document when you reach step 5.
3. Give the new palette a name. Then in the Swatches panel, right click on any two of the colors that have been automatically inserted, and select Delete, leaving just one colour which you can later delete.
4. Now you close the document. 
5. Create a blank new document. Choose FILE>PLACE and import the same image document you used in step 1. Duplicate it, and lock the background layer.
Now, with the duplicate layer selected, use the eyedropper from the Swatches Panel, select a colour in the image that you wish to keep, click on the well in the swatches panel, and it will load. Then click to add it to the swatches.  (Video attached.)
6. I did not do this in the video, but once you have one or two of your own swatches placed in your category, you can click on the initial swatch that was automatically selected and delete it.
7. Note that each time you add a swatch to your category, the duplicate layer will remain that colour. That is why you must keep deleting the duplicate layer and then creating a new duplicate.

 

Said it was fiddly! 

 

 

 

[walt.farrell]

That creates a palette of colors from the image, @jmwellborn, but how do you use it when exporting a Palletized PNG? The Export is the question here, I think.

[jmwellborn]

@walt.farrell I began by saying “If I understand your issue correctly…”. Apparently not. Oh well. Maybe it will give somebody else a laugh as well.🤪

[carl123]

20 hours ago, walt.farrell said:

Though you can specify Custom in the Export dialog, there does not seem to be any way of choosing a specific palette in that case.

I think Custom may have provided the ability to use a custom set/palette of colours but as you say that has a bug and has never worked.

 

@everyone

Could this somehow be done using a gradient map adjustment using sharp transitions (i.e. no gradients) between say, 4 custom colours as shown in example below? It sounds like it should work but the results look odd (in some places) even though the colours do appear to be restricted to the 4 chosen colours

(Original image on the left, 4 colour image on the right)

[lacerto]

This topic has been discussed multiple times on the forum, to some depth e.g. here:

For Windows users, it is probably easiest to use G'Mic plug-in and Photo. GIMP itself can be used for this, too (both to produce palettes and reduce colors with palettes).

If Affinity app alone is wished to be used, then using Gradient Map, Posterize (with exact number of colors specified) and Black and White  adjustments in this specific order can produce something similar (with exact number of colors and no shades in between). An alternative is using LUTs.

The result of course is not an indexed image because they are not supported in Affinity apps but the effect is similar.

Searching the forum using e.g. the following keywords should result in some hits: indexed, palette, palettized, color reduction, quantization, posterization, colorization