Turn: Java extracts pixels from a picture

This article transferred from: http://www.infosys.tuwien.ac.at/teaching/courses/WebEngineering/References/java/docs/api/java/awt/image/ Pixelgrabber.html

The PixelGrabber class implementation can attach a imageconsumer that obtains a subset of the image pixels on an image or ImageProducer object. Here is an example:

 public void Handlesinglepixel (int x, int y, int pixel) {int alpha = (pixel >>) & 0xFF;        int red = (pixel >>) & 0xFF;        int green = (pixel >> 8) & 0xFF;        int blue = (pixel) & 0xff; Deal with the pixel as necessary ...}        public void Handlepixels (Image img, int x, int y, int w, int h) {int[] pixels = new int[w * h];        PixelGrabber pg = new PixelGrabber (img, x, y, W, h, pixels, 0, W);        try {pg.grabpixels ();            } catch (Interruptedexception e) {System.err.println ("interrupted waiting for pixels!");        Return } if ((Pg.getstatus () & imageobserver.abort)! = 0) {System.err.println ("image fetch aborted or Erro            Red ");        Return } for (int j = 0; J < H; j + +) {for (int i = 0; i < W; i++) {Handlesinglepixel (x+i            , Y+j, Pixels[j * w + i]); }        } }

　　

PixelGrabber

PixelGrabber (Image img,                    int x,                    int y,                    int w,                    int h,                    int[] pix,                    int off,                    int scansize)

Creates a PixelGrabber object that fetches the pixel rectangle (x, Y, W, h) from the specified image into the given array. Stores the pixels in the array in the default RGB colormodel form. The RGB data in pixels (i, j) ((I, j) in the rectangle (x, Y, W, h) is stored in the array pix[(j-y) * scansize + (i-x) + off] position.

Parameters:

img -image from which to retrieve pixels

-The x-coordinate of the upper

x -left corner of the pixel rectangle retrieved from the image, relative to the default (non-scaled) image size

y -the upper-left corner of the pixel rectangle retrieved from the image y-coordinate

-the width of the

w pixel rectangle to retrieve

-the height of the

h pixel rectangle to retrieve

pix -an array of integers to hold the RGB pixels retrieved from the image

off -The offset of the first pixel

in the array

scansize -the distance between a row of pixels in the array and the next line of pixels

See also:

ColorModel.getRGBdefault()

PixelGrabber

 public  PixelGrabber  (Imageproducer ip, Int x, Int&nbs P;y, Int w, Int h, Int[] pix, I Nt off, Int scansize) 

The

creates a PixelGrabber object that crawls the pixel rectangle (x, Y, W, h) into the given array from the image generated by the specified imageproducer. Stores the pixels in the array in the default RGB colormodel form. The RGB data for pixels (i, j) ((I, j) in the rectangle (x, Y, W, h) is stored in the array   pix[(j-y) * scansize + (i-x) + off]   position.

 

Parameters:

IP  -generate images for   imageproducer, retrieving pixels from the image

x  -The x-coordinate of the upper-left corner of the pixel rectangle retrieved from the image, relative to the default (non-scaled) image size

y  -the upper-left corner of the pixel rectangle retrieved from the image

w  -The width of the pixel rectangle to retrieve

h  -the height of the pixel rectangle to retrieve

pix  -An integer array to hold the RGB pixels retrieved from the image

o FF  -The offset of the first pixel in the array

scansize The distance between a row of pixels in the  -array and the next line of pixels

See also:

colormodel.getrgbdefault ()

PixelGrabber

PixelGrabber (Image img,                    int x,                    int y,                    int w,                    int h,                    boolean Forcergb)

Creates a PixelGrabber object that captures the rectangular portion of the pixel (x, Y, W, h) from the specified image. If each call to SetPixels uses the same colormodel, it is stored as if it were the original ColorModel, otherwise the pixels are stored in the default RGB colormodel format. If the Forcergb parameter is true, the pixels will always be stored in the default RGB colormodel form. In either case, the PixelGrabber allocates a buffer to hold the pixels. if (W < 0) or (H < 0), they default to the width and height of the source data saved when the information is passed.

Parameters:

img -image to retrieve image data

from

x -The x-coordinate of the upper-left corner of the pixel rectangle retrieved from the image, relative to the default (not scaled) image size

y -The y-coordinate of the upper-left corner of the pixel rectangle retrieved from the image

w -width of the pixel rectangle to retrieve

h -the height of the pixel rectangle to retrieve

forceRGB -True if the pixel should always be converted to the default RGB ColorModel

Grabpixels

Grabpixels ()                   throws Interruptedexception

Requests that Image or imageproducer begin passing pixels, and waits for all pixels in the relevant rectangle to be passed.

Return:

Returns true if the pixel was successfully fetched, false if aborted, error, or timed out

Thrown:

InterruptedException -Another thread has interrupted this thread.

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