Re-sizing an image without losing quality

Question

I made this code to resize images with two factors. It works, but the quality of image is very bad after it is resized! Can you help me?

This is the code

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Answer 1

The do while loop used in The Perils of Image.getScaledInstance() will run into an infinite loop, given those values, w = 606; h = 505, targetWidth = 677, targetHeight = 505

Here is a simplied testing code, you can try it.

public class LoopTest {

    public static void main(String[] args) {
        new LoopTest(true, 606, 505, 677, 505);
    }

    public LoopTest(boolean higherQuality, int w, int h, int targetWidth, int targetHeight) {
        do {
            if (higherQuality && w > targetWidth) {
                w /= 2;
                if (w < targetWidth) {
                    w = targetWidth;
                }
            }

            if (higherQuality && h > targetHeight) {
                h /= 2;
                if (h < targetHeight) {
                    h = targetHeight;
                }
            }
        } while (w != targetWidth || h != targetHeight);        // TODO Auto-generated constructor stub
    }
}

A quick work around: define an index for loop count. If the index is >=10, break out of loop.