Develop Reference

How can I read every pixel of a WritableImage with Raster?

I have to write a method that:
Create a histogram
read all pixel values from grayscale images (variable width and height)
fill the histogram
How can I do it? I wrote a bit of code but I'm deadlocked.
public histogram(BufferedImage image){
WritableRaster writableRaster = image.getRaster();
int width = image.getWidth();
int height = image.getHeight();
int pixelValue;
for (int y = 0; y < height; y++) {
for (int x = 0; x < width; x++) {
pixelValue = writableRaster.setDataElements(x, y, width, height, );
}
}
}

The following code snippet should help:
Raster raster = image.getRaster();
int numBands = raster.getSampleModel().getNumBands();
int width = image.getWidth();
int height = image.getHeight();
for (int y = 0; y < height; y++) {
for (int x = 0; x < width; x++) {
int[] pixelValue = new int[numBands];
raster.getPixel(x, y, pixelValue);
}
}
If you really have a grayscale image without alpha, the SampleModel will contain only one band. In this case the pixelValue array will contain your desired int value. You only have to add an histogram array of 256 int values and increase the value at the index of your pixel value.

How to load pixel from one image in another

I'm new to Java and ImageJ and I'm trying to write a PluginFilter with ImageJ and Java. I want it to crop the right and left side of an image (500 pixel each), turn those parts 90 degrees to the outside and load them in a new image.
I already tried couple of options and now I got totally confused. I don't think there is any mistake in the algorith itself, but in the handling of ImageProcessor etc..
import ij.*;
import ij.process.*;
import ij.gui.*;
import java.awt.*;
import ij.plugin.filter.*;
public class Cropping28_Plugin implements PlugInFilter {
ImagePlus imp;
public int setup(String arg, ImagePlus imp){
imp = IJ.getImage();
this.imp = imp;
return DOES_ALL;
}
public void run(ImageProcessor ip){
// int[] p = null;
// int[] q = null;
int height = imp.getHeight();
int width = imp.getWidth();
// New Image
ImagePlus new_image = IJ.createImage("Nr1", "RGB", height, 500, 1);
// turning the picture for y=0:500 (left side of picture)
for(int x = 0; x < height; x++){
for(int y = 0; y < 500; y++){
int k = 0;
// loading pixel
int q = imp.getProcessor().getPixel(x, y);
int [] convert = {q, q, q};
// pixel in newimage
int a = height - k;
int b = x;
new_image.getProcessor().putPixel(a, b, convert);
k++;
}
}
// turning the picture for y=get.Length:get.Length-500 (right side of picture)
for(int x = 0; x < height; x++){
for(int y = width -500; y < width; y++){
int k = 0;
// loading pixel
int q = imp.getProcessor().getPixel(x, y);
int [] convert = {q, q, q};
// pixel in new image
int a = height - k;
int b = x;
new_image.getProcessor().putPixel(a, b, convert);
k++;
}
}
// draw new picture
new_image.show();
}
}
I expect the output to be a picture containing the pixel of the right and left edge of the original image. The actual output is a write image of the size I expect.
It would be awesome if someone had an idea!

Trying two different methods to transform a picture - JavaFX

So Im still learning Java. Now Im learning JavaFX.
I have a picture of a tree. And I want to try two different method. the first method I use was using unary operator to turn the image colour to grey.
Now I want to try a second method using the ColourTransformer interface that I made to get a 10 pixel wide gray frame replacing the pixels on the border of an image.
This is what I have done. for the second method, im not quite sure how to specify the pixel. Any suggestions?
this is what I have done
public class ColourFilter extends Application {
//Using Unary Operator to transform image to grayscale - Method 1
public static Image transform(Image in, UnaryOperator<Color> f) {
int width = (int) in.getWidth();
int height = (int) in.getHeight();
WritableImage out = new WritableImage(
width, height);
for (int x = 0; x < width; x++)
for (int y = 0; y < height; y++)
out.getPixelWriter().setColor(x, y,
f.apply(in.getPixelReader().getColor(x, y)));
return out;
}
public static <T> UnaryOperator<T> compose(UnaryOperator<T> op1, UnaryOperator<T> op2) {
return t -> op2.apply(op1.apply(t));
}
//Using ColourTransformer interface to get 10 pixel wide gray frame replacing the pixels on the border of an image - Method 2
public static Image transform(Image in, ColourTransformer f) {
int width = (int) in.getWidth();
int height = (int) in.getHeight();
WritableImage out = new WritableImage(
width, height);
for (int x = 0; x < width; x++)
for (int y = 0; y < height; y++)
out.getPixelWriter().setColor(x, y, f.apply(x, y, in.getPixelReader().getColor(x, y)));
return out;
}
#FunctionalInterface
interface ColourTransformer {
Color apply(int x, int y, Color colorAtXY);
}
public void start(Stage stage) {
Image image = new Image("amazing-trees.jpg");
Image image2 = transform(image, Color::brighter);
Image image3 = transform(image2, Color::grayscale);
// alternative to two previous image transforms -- composition
//Image image3 = transform(image, compose(Color::brighter, Color::grayscale));
stage.setScene(new Scene(new VBox(
new ImageView(image),
// new ImageView(image2),
new ImageView(image3))));
stage.show();
}
}

As the compile error message says, you are trying to call
f.apply(Color);
where f is a ColourTransformer: however you defined the apply method in ColorTransformer with three parameters: apply(int, int, Color).
You need to replace
f.apply(in.getPixelReader().getColor(x, y))
with
f.apply(x, y, in.getPixelReader().getColor(x, y))
i.e.
public static Image transform(Image in, ColourTransformer f) {
int width = (int) in.getWidth();
int height = (int) in.getHeight();
WritableImage out = new WritableImage(
width, height);
for (int x = 0; x < width; x++)
for (int y = 0; y < height; y++)
out.getPixelWriter().setColor(x, y, f.apply(x, y, in.getPixelReader().getColor(x, y)));
return out;
}
You can get the 10-pixel gray border by doing:
Image image = new Image("amazing-trees.jpg");
int width = (int) image.getWidth();
int height = (int) image.getHeight();
Image framedImage = transform(image, (x, y, color) -> {
if (x < 10 || y < 10 || width - x < 10 || height - y < 10) {
return Color.GRAY ;
} else return color ;
});

Index pixels to color certain location of pictures

I'm creating a method that takes two parameters with 2 indexes a start and an end that takes a location of the picture being edited and turn those pixels to a different color. Using a while loop to index start and end.
The problem I'm having is I'm only a getting a really small portion to change color:
Don't mind some of the code that is commented out. I was trying a bunch of different things.
public void negative(int start, int end)
{
Pixel[] pixelArray = this.getPixels(); //pixelarray index
Pixel pixel = null;
// int height = this.getHeight();
//int paintPoint = height / 2;
//int width = this.getWidth();
int i = 0;
int red, green, blue = 0;
// int x = 0;
Pixel topPixel = null;
Pixel bottomPixel = null;
//int startY;
//int startX;
int y = start;
int x = end;
//int count;
while( y < this.getHeight())
{
y++;
while (x < this.getWidth()) //loops through index
{
pixel = this.getPixel(x,y);
red = pixel.getRed();
green = pixel.getGreen();//collects color green
blue = pixel.getBlue();//collects color blue
Color negColor = new Color( 255 - red, 255 - green, 255 - blue);//sets new values of pixels
pixel.setColor(negColor);
x++;
//count = count + 1;
i++;//indexes continuing
}
}
}

A picture is 2D yet you are treating it as 1D (notice after once through your inner x loop it never is reset to its min value). If you wish to color an arbitrary rectangle within a given photo the parms should include two points : minx, miny and maxx maxy then your pair of 2D loops visits each point in that region line by line.
// do sanity checks on your parms
if (this.getWidth() < maxx) {
maxx = this.getWidth();
}
if (this.getHeight() < maxy) {
maxy = this.getHeight();
}
if (minx < 0) {
minx = 0;
}
if (miny < 0) {
miny = 0;
}
for (y = mixy; y < maxy; y++) {
for (x = mixx; x < maxx; x++) {
// now your have valid x and y values
}
}

How to get average RGB value of Bitmap on Android?

I know how to get the RGB values of individual pixels of a bitmap. How can I get the average RGB value for all of the pixels of a bitmap?

I think below code for exact answer to you.
Get the Average(Number of pixels)of Red, Green and Blue value for the given bitmap.
Bitmap bitmap = someBitmap; //assign your bitmap here
int redColors = 0;
int greenColors = 0;
int blueColors = 0;
int pixelCount = 0;
for (int y = 0; y < bitmap.getHeight(); y++)
{
for (int x = 0; x < bitmap.getWidth(); x++)
{
int c = bitmap.getPixel(x, y);
pixelCount++;
redColors += Color.red(c);
greenColors += Color.green(c);
blueColors += Color.blue(c);
}
}
// calculate average of bitmap r,g,b values
int red = (redColors/pixelCount);
int green = (greenColors/pixelCount);
int blue = (blueColors/pixelCount);

The answer from john sakthi does not work correctly if the Bitmap has transparency (PNGs). I modified the answer for correctly getting the red/green/blue averages while accounting for transparent pixels:
/**
* Calculate the average red, green, blue color values of a bitmap
*
* #param bitmap
* a {#link Bitmap}
* #return
*/
public static int[] getAverageColorRGB(Bitmap bitmap) {
final int width = bitmap.getWidth();
final int height = bitmap.getHeight();
int size = width * height;
int pixelColor;
int r, g, b;
r = g = b = 0;
for (int x = 0; x < width; ++x) {
for (int y = 0; y < height; ++y) {
pixelColor = bitmap.getPixel(x, y);
if (pixelColor == 0) {
size--;
continue;
}
r += Color.red(pixelColor);
g += Color.green(pixelColor);
b += Color.blue(pixelColor);
}
}
r /= size;
g /= size;
b /= size;
return new int[] {
r, g, b
};
}

you can use this method for this purpose: Bitmap.createBitmap
For instance:
int[] colors = new int[yourWidth * yourHeight];
Arrays.fill(colors, Color.Black);
Bitmap bitamp = Bitamp.createBitmap(colors, yourWidth, yourHeight, Bitmap.Config.ARGB_8888);
Check for typo