loadPixels or get() does not return valid colors on transparent images

Programming Questions

cablesrv

loadPixels or get() does not return valid colors on transparent images

in Programming Questions • 1 month ago

Using 2.0.3 and loadPixels and get() just goes nuts on a background image with transparency. It seems to only pick up white/black/transparent no other colors.

PImage myImage;
color c;
void setup(){
size(1200, 760);
myImage = loadImage("background1.png");
image(myImage, 0, 0, myImage.width, myImage.height);
}
void draw(){
loadPixels();
c = pixels[mouseX + mouseY * myImage.width];
fill(c);
noStroke();
rect(500, 350, 50, 50);
println(c);
}

background1.png is a image that has certain areas transparent. When filling the rect with mouse color it does not work. If I remove transparency entirely it works fine. Can anyone explain how to get pixel color off images that are transparent?

Replies(2)

cablesrv

Re: loadPixels or get() does not return valid colors on transparent images

1 month ago

nm, found that I can't just call loadPixels by itself to read data it needs to be called via the image it needs to read. In this instance it should be

myImage.loadPixels();

and

myImage.pixels[mouseX + mouseY * myImage.width];

doing this solved the issue and returns correct RGB values as it should.

GoToLoop

Re: loadPixels or get() does not return valid colors on transparent images

1 month ago

The reason you failed to read the transparent property directly from sketch's canvas
is that all transparent colors are converted to its corresponding opaque color when it's rasterized to the canvas.
In short, there's no transparent colors in the main canvas PGraphics.

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