Android Question image processing

[zmrcic]

how can I convert image to int() array? found to byte(), but not to int
I want to get black-white int() from image. image should be first converted to base64.
this is java example....pixel by pixel

canvas.toDataURL('image/jpeg').replace(/^data:image\/(png|jpg|jpeg);base64,/, "");

private static void convertARGBToGrayscale(int[] argb, int width, int height) {
        int pixels = width * height;

        for(int i = 0; i < pixels; ++i) {
            int r = argb[i] >> 16 & 255;
            int g = argb[i] >> 8 & 255;
            int b = argb[i] & 255;
            int color = r * 19 + g * 38 + b * 7 >> 6 & 255;
            argb[i] = color;
        }

    }

thx

 

[Sandman]

I'd recommend adding what you have in the beginning, and what your desired end result is. Perhaps there's an easier route.

 

[klaus]

You might have a look at the BitmapCreator library.
You may also have a look at the B4X Graphics Booklet
chapter 2.5 BitmapCreator explanations
chapter 2.9.1 BitmapCreatorDemo1 demo program

 

[zmrcic]

thx klaus and Sandman...I think it is casting problem....
colors are from 16777215(white) to 0(black), so if I iterate over pixels I can get int of each pixel, like so

            Dim color As Int = BM.GetPixel(x, y)
            Dim res(4) As Int
            res(0) = Bit.UnsignedShiftRight(Bit.And(color, 0xff000000), 24)
            res(1) = Bit.UnsignedShiftRight(Bit.And(color, 0xff0000), 16)
            res(2) = Bit.UnsignedShiftRight(Bit.And(color, 0xff00), 8)
            res(3) = Bit.And(color, 0xff)

I think Erel wrote this, it should be equivalent to

             int r = argb[i] >> 16 & 255;
            int g = argb[i] >> 8 & 255;
            int b = argb[i] & 255;

but
int color = r * 19 + g * 38 + b * 7 >> 6 & 255
give me cast type error, tried many things like
Dim color As Byte =Bit.ShiftRight(r * 19 + g * 38 + b * 7 , 6 ) And 255
but I need int here, not byte
Sandman, this code is part of old(new for me ) problem for printing image on BT printer. My printer(declared as ESC/POS?!) does not print images with libraries I found on B4x, so I have to roll my own. Can publish complete code if you think it will help. At the moment I can only print black box(filling that int() with 0), but I have to read it from locally stored image. So my code is OK, it can print, arrays and commands are OK, but image conversion is not.
thx again

 

[Erel]

Moved to the questions forum.

 

[Erel]

Note that BitmapCreatorEffects includes this feature.

[B4X] BitmapCreator Effects

BitmapCreatorEffects class includes all kinds of very simple to use image effects. The class is cross platform and compatible with B4J (v6.3+), B4A (v8.3+) and B4i (v5.0+). Example: 'Greyscale an image: Dim GreyImage As B4XBitmap = effects.GreyScale(ExistingBmp) 'Blur an image: Dim BlurImage As...

www.b4x.com

Don't use Bitmap.GetPixel unless the image is very very small. Use BitmapCreator.