Using my custom colormap in Java for images
- by John
Hi everyone!
I've got a question concering a colormapping via index.
I tried this code found on
http://www.podgoretsky.pri.ee/ftp/Docs/Java/Tricks%20of%20the%20Java%20Programming%20Gurus/ch12.htm
// Gradient.java
// Imports
import java.applet.Applet;
import java.awt.;
import java.awt.image.;
public class Gradient extends Applet {
final int colors = 32;
final int width = 200;
final int height = 200;
Image img;
public void init() {
// Create the color map
byte[] rbmap = new byte[colors];
byte[] gmap = new byte[colors];
for (int i = 0; i < colors; i++)
gmap[i] = (byte)((i * 255) / (colors - 1));
// Create the color model
int bits = (int)Math.ceil(Math.log(colors) / Math.log(2));
IndexColorModel model = new IndexColorModel(bits, colors,
rbmap, gmap, rbmap);
// Create the pixels
int pixels[] = new int[width * height];
int index = 0;
for (int y = 0; y < height; y++)
for (int x = 0; x < width; x++)
pixels[index++] = (x * colors) / width;
// Create the image
img = createImage(new MemoryImageSource(width, height, model,
pixels, 0, width));
}
public void paint(Graphics g) {
g.drawImage(img, 0, 0, this);
}
}
It worked great but I tried to load a custom image jpeg mapped on my own colormap but it didnt work right. I saw only a bunch of green and blue pixels drawn on a white background.
My custom color map method here:
public void inintByteArrays() {
double[][] c = // basic color map
{ { 0.0000, 0.0000, 0.5625 }, { 0.0000, 0.0000, 0.6250 },
{ 0.0000, 0.0000, 0.6875 }, { 0.0000, 0.0000, 0.6875 },
{ 0.0000, 0.0000, 0.7500 }, { 0.0000, 0.0000, 0.8125 },
{ 0.0000, 0.0000, 0.8750 }, { 0.0000, 0.0000, 0.9375 },
{ 0.0000, 0.0000, 1.0000 }, { 0.0000, 0.0625, 1.0000 },
{ 0.0000, 0.1250, 1.0000 }, { 0.0000, 0.1875, 1.0000 },
{ 0.0000, 0.2500, 1.0000 }, { 0.0000, 0.3125, 1.0000 },
{ 0.0000, 0.3750, 1.0000 }, { 0.0000, 0.4375, 1.0000 },
{ 0.0000, 0.5000, 1.0000 }, { 0.0000, 0.5625, 1.0000 },
{ 0.0000, 0.6250, 1.0000 }, { 0.0000, 0.6875, 1.0000 },
{ 0.0000, 0.7500, 1.0000 }, { 0.0000, 0.8125, 1.0000 },
{ 0.0000, 0.8750, 1.0000 }, { 0.0000, 0.9375, 1.0000 },
{ 0.0000, 1.0000, 1.0000 }, { 0.0625, 1.0000, 0.9375 },
{ 0.1250, 1.0000, 0.8750 }, { 0.1875, 1.0000, 0.8125 },
{ 0.2500, 1.0000, 0.7500 }, { 0.3125, 1.0000, 0.6875 },
{ 0.3750, 1.0000, 0.6250 }, { 0.4375, 1.0000, 0.5625 },
{ 0.5000, 1.0000, 0.5000 }, { 0.5625, 1.0000, 0.4375 },
{ 0.6250, 1.0000, 0.3750 }, { 0.6875, 1.0000, 0.3125 },
{ 0.7500, 1.0000, 0.2500 }, { 0.8125, 1.0000, 0.1875 },
{ 0.8750, 1.0000, 0.1250 }, { 0.9375, 1.0000, 0.0625 },
{ 1.0000, 1.0000, 0.0000 }, { 1.0000, 0.9375, 0.0000 },
{ 1.0000, 0.8750, 0.0000 }, { 1.0000, 0.8125, 0.0000 },
{ 1.0000, 0.7500, 0.0000 }, { 1.0000, 0.6875, 0.0000 },
{ 1.0000, 0.6250, 0.0000 }, { 1.0000, 0.5625, 0.0000 },
{ 1.0000, 0.5000, 0.0000 }, { 1.0000, 0.4375, 0.0000 },
{ 1.0000, 0.3750, 0.0000 }, { 1.0000, 0.3125, 0.0000 },
{ 1.0000, 0.2500, 0.0000 }, { 1.0000, 0.1875, 0.0000 },
{ 1.0000, 0.1250, 0.0000 }, { 1.0000, 0.0625, 0.0000 },
{ 1.0000, 0.0000, 0.0000 }, { 0.9375, 0.0000, 0.0000 },
{ 0.8750, 0.0000, 0.0000 }, { 0.8125, 0.0000, 0.0000 },
{ 0.7500, 0.0000, 0.0000 }, { 0.6875, 0.0000, 0.0000 },
{ 0.6250, 0.0000, 0.0000 }, { 0.5625, 0.0000, 0.0000 },
{ 0.5000, 0.0000, 0.0000 } };
for (int i = 0; i < c.length; i++) {
for (int j = 0; j < c[i].length; j++) {
if (j == 0)
r[i] = (byte) ((byte) c[i][j]*255);
if (j == 1)
g[i] = (byte) ((byte) c[i][j]*255);
if (j == 2)
b[i] = (byte) ((byte) c[i][j]*255);
}
}
My question is how I can use my colormap for any image I want to load and map in the right way. Thank you very much!
Greetings, protein1.
