CODEWITHSUNDEEP
javaandroidimagebitmapfiltering
ojoj kolol
ojoj kolol

Reputation: 79

Scale up small bitmap pixel perfectly

I am making a pixel game for android. I am using 32x32 images. To make the game appear the same regardless of screen-dimensions i dynamically scale up the images. My issue is that when scaling up, parts of the images does not keep their original color:

6 tiles, just before the black edges there is an unwanted shadowy line (presumably the average of the black and the redish color)

6 tiles, originally 32x32. As you can see, just before the black edges there is an unwanted shadowy line (presumably the average of the black and the redish color).

This is the code i use for scaling:

public abstract class Drawable {
    protected int x;
    protected int y;
    protected Bitmap image;

    Drawable(Bitmap image, int x, int y, float scale) {
        this.x = x;
        this.y = y;
        this.image =  Bitmap.createScaledBitmap(image, (int)(image.getWidth()*scale), (int)(image.getHeight()*scale), false);
    }

    abstract void draw(Canvas canvas);
}

As you can see i am not using the filter. This would make the edge-area more blurry. Are there another filter that in contrast to if i where to use true when scaling up actually perserves the crispness of the image?

Edit:

I now tried this approach instead:

 scaledRect = new RectF(x, y, x+image.getWidth()*scale, y+image.getHeight()*scale);
    paint = new Paint();
    paint.setAntiAlias(false);
    paint.setDither(false);
    paint.setFilterBitmap(false);

And in the draw call:

canvas.drawBitmap(this.image, null, scaledRect, paint);

With no success...

Upvotes: 0

Views: 976

Answers (1)

shiftpsh
shiftpsh

Reputation: 1926

Android processes bitmap scaling with bilinear interpolation algorithm by default. What you're trying to do is nearest neighbor interpolation.

Make a Paint, turn off dither and anti-alias, don't draw by createScaledBitmap and try this:

paint.setDither(false);
paint.setAntiAlias(false);

canvas.drawBitmap(bitmap, null, new RectF(left, top, width, height), paint);

Upvotes: 1

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