Image.getRGB() problem

[daregazi]

I am having a serious problem with the Image.getRGB() method.

Suppose I have a specific ARGB byte array and I create an image of it. The thing is when I try to obtain the ARGB array of the new image again using the getRGB() method, the resulting array is not exactly the previous one which I just made the image based on! There are slightly differences between the two arrays. In this example according to my observation one bit of the all red and green and blue bytes have changed, mostly the alpha byte without any changes.

I read the J2ME Image.getRGB() API which says:
"The returned values are not guaranteed to be identical to values from the original source, such as from createRGBImage or from a PNG image. Color values may be resampled to reflect the display capabilities of the device (for example, red, green or blue pixels may all be represented by the same gray value on a grayscale device). "

I desperately need your help how to overcome this problem. I just need the original RGB!!
Please do reply anyone who has a solution!

[jappit]

Hi daregazi,

as you've read from getRGB() JavaDocs, that is the exact behaviour of this method. To get precise pixel color informations, afaik, there's no other way than implementing your image decoder (for the formats you need).. or search for existing ones (but I'm not aware of any Java ME ones)

Pit

[daregazi]

thanks Jappit,

As you said I have had looked at a PNG decoder in J2SE, do you think if I try to adapt it to J2ME and replace the getRaster() method correspondingly with getRGB(), my problem will be solved?
My concern is even having a specific png decoder, I still need to use the same method getRGB(), and it would return the RGB array arbitrarily!!!

What do you think?
cheers

[jappit]

If you manage to manually read/decode your PNG image with a custom image decoder, then you should have total access to all PNG informations, so also original colors information should be available.

Pit

Edit: obviously, your PNG decoder should not give you back a javax.microedition.lcdui.Image instance, since you would fall back in the previous case, so having the getRGB() method returning the "adapted" color values. Your custom decoder should instead return you a custom object, from which you can easily retrieve the PNG informations you need.