Image processing

[popprem]

Hi,

I have a requirement to calculate the blue colored area in an JPG image. Can anyone suggest me a way to do this please?

References for any libraries or APIs are highly appreciated.

Thanks in advance.

Regards,
Prasath.

[chaarmann]

Just convert the image into a RGB-bitmap where a pixel is 3 bytes (red, green, blue). Then loop through the bytes of the bitmap and count the ones with a blue color. For example "0x0000FF" is a 100% blue dot. But maybe you also want slightly lighter or darker blue dots to be recognized, because the source was jpg, so you should define a derivation value accordingly. For example if you define value=3, then "0x0300FC" would also count as blue dot.

The java Image-IO is included since JDK1.4. Just read the normal API for it. (for example javax.imageio.I mageIO.Buffered Image)

[popprem]

Hi Chaarmann,

Thanks a lot for the reply. Yeah, i too got the point about
iterating pixels. I get jpg images as input for this
program. So can i do the image conversion from jpg to bytes
in the code level?

Please provide me a sample.

Thanks.

[chaarmann]

Have you looked up the API I mentioned?
I have no time to do that right now, but there should be a single command to load an image of type jpg from disk into memory. And another command to directly access the image buffer. I think you need to convert the image to bmp before accessing the image buffer, so that you have rgb-values inside the buffer or you don't need to convert and can get the pixel direcly with "int rgb = bufferedImage.g etRGB(x, y)", but I can't remember exactly. You can find a lot of code examples if you google for "java Image-IO" or some of its classes.

[popprem]

Thanks for your reply Chaarmann. I got the hight and width
of the image, iterating through them and checking for blue
color pixels using "int rgb = bufferedImage.g etRGB(x, y)"
and checking rgb for 0x0000FF.

Thanks a lot.