Color grading pixels only - preserving background

[Fredrik Ingvarson]

Hi all,

I'm new to the forum! I have searchied on the forum for a solution but I'm a newbie so I don't even know how to formulate my question properly. What I'm trying to do is the following:

I have a png file of a fractal triangle. The pixels in the png are all white and the background is transparent (in the picture below I have added a black background in Affinity Photo 2 so that the white pixles can be seen).

Next I would like to recolor the white dots only with a gradient ranging from light blue at the edges of the large triangle to black (or transparent) in the center of the large triangle.

How can I do this?

I have tried the gradient tool but I can't figure out how to do this. Reading different instructions on similar (?) topices I imagine that I want to have a gradient fill (light blue to black/transparent) while protecting the alpha so that only the white pixels are affected and not the background.

Any suggestions?

Br,
Fredrik

[Komatös]

Hi @Fredrik Ingvarson and welcome to the forum.

Use the Rectangle tool to create a rectangle with the same height and width as the triangle.
Select the Gradient tool, select the type and create the gradient and use it to create the fill of the rectangle.
In Studio Layers drag the rectangle layer onto the pixel layer with the triangles (onto the text area). 

 

 

[v_kyr]

Even in APh I would use a vector representation of a Sierpinsky triangle as that offers overall easier handling, not only for applying gradients and the like but also for scaling up-/down etc.

• Sierpinski-Triangle.afphoto
• Sierpinski-Triangle.svg

 

[walt.farrell]

1 hour ago, Komatös said:

Use the Rectangle tool to create a rectangle with the same height and width as the triangle.
Select the Gradient tool, select the type and create the gradient and use it to create the fill of the rectangle.
In Studio Layers drag the rectangle layer onto the pixel layer with the triangles (onto the text area). 

You could instead apply a Gradient Overlay effect to the pixel layer.

But neither your approach nor mine can, as far as I know, exactly match the request for a gradient that runs from the edges of the large triangle to the center. A radial gradient is possible, but it's not exactly correct for that request.

Perhaps breaking up the large triangle into 3 smaller triangles, meeting at the center of the large triangle, and applying linear gradients to each?

 

[Fredrik Ingvarson]

Thank you all for helping me!

I used the method suggested by @Komatös and used an elliptical gradient. Now I have something I can work on. Thank you also for the other suggestions. It really helps!

/Fredrik

[v_kyr]