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Index › Programming Questions & Help › Programs › saving image file with transparency problem
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saving image file with transparency problem (Read 539 times)
crimson
saving image file with transparency problem
Oct 12th, 2008, 3:49pm  
hello,

i'm writing a small program to concatenate a group of similar tga images into one column of images and to save the result into a tga file respecting the transparency of sourced tga images in the resulting one.

i've already written program that makes it whithout respect to transparency and now i need some help to upgrade it to the fully functional one.

in reference i've found the PGraphics object that possibly could help me with my problem, but i have no idea how to use it in my case.

this is my code:

int i;
int n = 100;
size(50, n*50);
PImage a;
for(i=1;i<=n;i++) {
a = loadImage("knob"+i+".tga");
image(a, 0, i*50-50);
}
save("knob_concat.tga");
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antiplastik
Re: saving image file with transparency problem
Reply #1 - Oct 12th, 2008, 10:29pm  
save() method's reference says :
Quote:
All images saved from the main drawing window will be opaque. To save images without a background, use createGraphics().


So you'll have to draw your images on a buffer :

Code:
int i;  
int n = 100;
size(50, n*50);
PGraphics pg = createGraphics(width, height, P3D);
PImage a;
for(i=1;i<=n;i++) {
  a = loadImage("knob"+i+".tga");
  pg.image(a, 0, i*50-50);
}
pg.save("knob_concat.tga");
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crimson
Re: saving image file with transparency problem
Reply #2 - Oct 13th, 2008, 8:40am  
i've tried this just now, antiplastik. resulting image is still opaque. only background color is changed from grey to black.
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PhiLho 
Re: saving image file with transparency problem
Reply #3 - Oct 15th, 2008, 7:05pm  
Works with JAVA2D instead of P3D:
Code:
PImage bigImage;
int n = 6;
int IMAGE_SIZE = 48;

void setup()
{
  PGraphics bigImage = createGraphics(IMAGE_SIZE, IMAGE_SIZE * n, JAVA2D);
  bigImage.beginDraw();
  for (int i = 0; i < n; i++)
  {
    PImage tpi = loadImage("E:/temp/testImage" + (i + 1) + ".png");
    bigImage.image(tpi, 0, i * IMAGE_SIZE);
  }
  bigImage.endDraw();
  bigImage.save("BigImage.png");
  exit();
}
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crimson
Re: saving image file with transparency problem
Reply #4 - Oct 16th, 2008, 8:17pm  
this one really works.
thank you, PhiLho. you're the best Smiley
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