Develop Reference

LWJGL - Get part of image byte buffer

Hello I am fairly new to OpenGL and LWJGL
I have loaded an Image into a ByteBuffer using the STBImage binding in LWJGL. I can draw the image to the screen, this works perfectly fine.
Now I want to "slice" an image into multiple smaller images. I need it for my Tileset system
I only got it working to slice the image into the individual tiles.
But they are not correctly drawn. I think I know what the problem is, but I don't really get it to work how it should.
I think this is the problem:
int s = x * 4 + y * 4;
Here is the entire slicing function.
private void sliceTileset(Image[] images, float tileWidth, float tileHeight) {
// The pixelbuffer of the entire tileset image (Loaded via STBImage.stbi_load)
ByteBuffer tilesetPixelBuffer = tilesetImage.getPixelBuffer();
int xOffset = 0;
int yOffset = 0;
// Loop over all available tile slots ((tileSetWidth / tileWidth) +
// (tileSetHeight / tileHeight))
for (int i = 0; i < images.length; i++) {
ByteBuffer buffer = ByteBuffer.allocateDirect((int) (tileWidth * tileHeight * 4));
for (int y = 0; y < tileHeight; y++) {
for (int x = xOffset; x < tileWidth + xOffset; x++) {
int s = x * 4 + y * 4;
// get the pixel from the tileset image buffer
int r = tilesetPixelBuffer.get(s);
int g = tilesetPixelBuffer.get(s + 1);
int b = tilesetPixelBuffer.get(s + 2);
int a = tilesetPixelBuffer.get(s + 3);
// put it into the tile image buffer
buffer.put((byte) r);
buffer.put((byte) g);
buffer.put((byte) b);
buffer.put((byte) a);
}
}
// Create a new image with the tile image buffer
images[i] = new Image(buffer, tileWidth, tileHeight);
buffer.flip();
// Offset the x-position for the next tile
xOffset += tileWidth;
// Offset the y-position for the next tile
yOffset += tileHeight; // Currently does nothing
}
}
If your need more information just ask for it!

Tensorflow in Android: java.lang.illegalArgumentsException

I want to put a tensorflow model on Anroid.
I recently noticed that the results of running the same data in Python and Android, respectively, are inconsistent.
After several trial and error, I found that the input data I entered when I ran the model on Android was wrong.
It was just a java.lang.IllegalArgumentException error, and I think I put the data correctly, but I have no idea what went wrong.
I used images that were transformed into image resizing and gray scale as learning data. in Python
I did the same preprocessing on Android.
My image type is .jpg
I attached my source.
Source related to image preprocessing
btntrans.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
try {
image_bitmap = resizeBitmapImage(image_bitmap, 28);
image_bitmap = RGB2GRAY(image_bitmap);
image.setImageBitmap(image_bitmap);
byte[] byteArrayRes = bitmapToByteArray(image_bitmap);
float[] inputArray = bytetofloat(byteArrayRes);
activityPrediction(inputArray);
}
catch(Exception e){
}
}
});
Everything happens when I click the button
resizeBitmapImage method
public Bitmap resizeBitmapImage(Bitmap source, int maxResolution)
{
int width = source.getWidth();
int height = source.getHeight();
int newWidth = width;
int newHeight = height;
float rate = 0.0f;
if(width > height)
{
if(maxResolution < width)
{
rate = maxResolution / (float) width;
newHeight = (int) (height * rate);
newWidth = maxResolution;
}
}
else
{
if(maxResolution < height)
{
rate = maxResolution / (float) height;
newWidth = (int) (width * rate);
newHeight = maxResolution;
}
}
return Bitmap.createScaledBitmap(source, newWidth, newHeight, true);
}
RGB2GRAY method
public Bitmap RGB2GRAY(Bitmap image){
int width = image.getWidth();
int height = image.getHeight();
Bitmap bmOut;
bmOut = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_4444);
for(int x = 0; x < width; x++){
for(int y = 0 ; y < height; y++){
int pixel = image.getPixel(x, y);
int A = Color.alpha(pixel);
int R = Color.red(pixel);
int G = Color.green(pixel);
int B = Color.blue(pixel);
R = G = B = (int)(0.299 * R + 0.587 * G + 0.114 * B);
bmOut.setPixel(x, y, Color.argb(A, R, G, B));
}
}
return bmOut;
}
bitmap to byte array method
private byte[] bitmapToByteArray(Bitmap bitmap){
ByteArrayOutputStream stream = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.JPEG, 100, stream);
return stream.toByteArray();
}
bytetofloat method
public float[] bytetofloat(byte[] array){
int[] returnArr = new int[array.length/4];
float[] returnArr1 = new float[array.length/4];
for(int i = 0 ; i < returnArr.length; i++){
//array[i] = 0;
returnArr[i] = array[i*4] & 0xFF;
if(returnArr[i] < 0 || returnArr[i]>255)
Log.d("ARRAY", returnArr[i]+" ");
returnArr1[i] = (float)returnArr[i];
}
return returnArr1;
}
When I run it with the above source, I get this error exactly.
java.lang.IllegalArgumentException: buffer with 308 elements is not
compatible with a Tensor with shape [1, 28, 28]
28 * 28 is Input image size
Before image resizing, it had an average width of 20 and a height of 36.
The strange thing is that the number 308 is changed to 306, 307 and fixed.
What can i do?

Here is my method for converting Java BufferedImage to Tensor object:
private static Tensor<?> convertImageToArray(BufferedImage bf) {
int width = bf.getWidth();
int height = bf.getHeight();
float[][][][] rgbArray = new float[1][height][width][3];
for (int i = 0; i < height; i++) {
for (int j = 0; j < width; j++) {
bf.getRaster().getPixel(i, j, rgbArray[0][i][j]);
}
}
return Tensor.create(rgbArray);
}
Your problem is probably in missed channels of your image. Float array length must be equal to
height * width * channels
of the image.

I try to rotat without lib but it make black points in picture

I am trying to rotate image without standard method , making color array and manipulate it, but when I invoke the, rotation I get black points (look the picture)
Here is my code, colScaled is the picture I am trying to convert to an array:
public void arrays() {
colScaled = zoom2();
int j = 0;
int i = 0;
angel = Integer.parseInt(this.mn.jTextField1.getText());
float degree = (float) Math.toRadians(angel);
float cos = (float) Math.cos(degree);
float sin = (float) Math.sin(degree);
int W = Math.round(colScaled[0].length * Math.abs(sin) + colScaled.length * Math.abs(cos));
int H = Math.round(colScaled[0].length * Math.abs(cos) + colScaled.length * Math.abs(sin));
int x;
int y;
int xn = (int) W / 2;
int yn = (int) H / 2;
int hw = (int) colScaled.length / 2;
int hh = (int) colScaled[0].length / 2;
BufferedImage image = new BufferedImage(W + 1, H + 1, im.getType());
for (i = 0; i < colScaled.length; i++) {
for (j = 0; j < colScaled[0].length; j++) {
x = Math.round((i - hw) * cos - (j - hh) * sin + xn);
y = Math.round((i - hw) * sin + (j - hh) * cos + yn);
image.setRGB(x, y, colScaled[i][j]);
}
}
ImageIcon ico = new ImageIcon(image);
this.mn.jLabel1.setIcon(ico);
}

Notice this block in your code :-
for (i = 0; i < colScaled.length; i++) {
for (j = 0; j < colScaled[0].length; j++) {
x = Math.round((i - hw) * cos - (j - hh) * sin + xn);
y = Math.round((i - hw) * sin + (j - hh) * cos + yn);
image.setRGB(x, y, colScaled[i][j]);
}
}
The x and y is pixel coordinate in source image (colScaled).
The objective of this code is to fill all pixels in destination image (image).
In your loop, there is no guarantee that all pixels in the destination image will be filled, even it is in the rectangle zone.
The above image depict the problem.
See? It is possible that the red pixel in the destination image will not be written.
The correct solution is to iterating pixel in destination image, then find a corresponding pixel in source image later.
Edit: After posting, I just saw the Spektre's comment.
I agree, it seems to be a duplicated question. The word "pixel array" made me thing it is not.

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

Fastest way to load thumbnail pixel values into Java

I need to be able to load RGB pixel values at a certain resolution into Java. That resolution is small (~300x300).
Currently, I've been loading them like this:
File file = new File("...path...");
BufferedImage imsrc = ImageIO.read(file);
int width = imsrc.getWidth();
int height = imsrc.getHeight();
int[] data = new int[width * height];
imsrc.getRGB(0,0, width, height, data, 0, width);
and then downsizing it myself.
Sam asked for the down-sizing code, so here it is:
/**
* DownSize an image.
* This is NOT precise, and is noisy.
* However, this is fast and better than NearestNeighbor
* #param pixels - _RGB pixel values for the original image
* #param width - width of the original image
* #param newWidth - width of the new image
* #param newHeight - height of the new image
* #return - _RGB pixel values of the resized image
*/
public static int[] downSize(int[] pixels, int width, int newWidth, int newHeight) {
int height = pixels.length / width;
if (newWidth == width && height == newHeight) return pixels;
int[] resized = new int[newWidth * newHeight];
float x_ratio = (float) width / newWidth;
float y_ratio = (float) height / newHeight;
float xhr = x_ratio / 2;
float yhr = y_ratio / 2;
int i, j, k, l, m;
for (int x = 0; x < newWidth; x ++)
for (int y = 0; y < newHeight; y ++) {
i = (int) (x * x_ratio);
j = (int) (y * y_ratio);
k = (int) (x * x_ratio + xhr);
l = (int) (y * y_ratio + yhr);
for (int p = 0; p < 3; p ++) {
m = 0xFF << (p * 8);
resized[x + y * newWidth] |= (
(pixels[i + j * width] & m) +
(pixels[k + j * width] & m) +
(pixels[i + l * width] & m) +
(pixels[k + l * width] & m) >> 2) & m;
}
}
return resized;
}
Recently, I realized that I can down-size with ImageMagick's 'convert' and then load the down-sized version that way. This saves additional 33%.
I was wondering, if there's an even better way.
EDIT: I realized that some people would wonder if my code is good in general, and the answer is NO. The code I used works well for me, because I down-size already small images (say 640x480, otherwise .getRGB() takes forever) and I don't care if a couple of color points spill over (carry-over from addition), and I know some people really care about that.

Here's a very good article on generating thumbnails in Java in an optimal way:
http://today.java.net/pub/a/today/2007/04/03/perils-of-image-getscaledinstance.html
You may have better results with specifying different scaling/rendering parameters.
Graphics2D g2 = (Graphics2D)g;
int newW = (int)(originalImage.getWidth() * xScaleFactor);
int newH = (int)(originalImage.getHeight() * yScaleFactor);
g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
RenderingHints.VALUE_INTERPOLATION_NEAREST_NEIGHBOR);
g2.drawImage(originalImage, 0, 0, newW, newH, null);