So I'm making some rgba images pixel by pixel following a certain pattern and saving them as png later on and noticed that when alpha channel es changed with certain colors it changes the whole pixel color when stored as png.
I made a test to show what is currently happening:
img := image.NewRGBA(image.Rect(0, 0, 250, 250))
for y := 0; y < height; y++ {
for x := 0; x < width; x++ {
f.Read(b)
img.SetRGBA(x, y, color.RGBA{
249,
214,
133,
255,
})
}
}
var buff bytes.Buffer
err := png.Encode(&buff, img)
if err != nil {
log.Println(err)
return
}
This will print an image of color #F9D685. But if I change alpha into 200 it will print another one with #6844BC and transparency instead of printing the original color with it's transparency.
Is there a way to solve this? I believe that it's because I'm missing something but can't really figure it out and didn't find anything similar to what's happening to me on google/here.
That one is simple:
go doc color.RGBA
package color // import "image/color"
type RGBA struct { R, G, B, A uint8 }RGBA represents a traditional 32-bit alpha-premultiplied color, having 8 bits for each of red, green, blue and alpha.
An alpha-premultiplied color component C has been scaled by alpha (A), so has valid values 0 <= C <= A.
You might be looking for color.NRGBA.
(Always, really always, consult the documentation of the involved types and functions. Always.)