have to use different image types, depending on the OS. how?

[linuxadmin]

hello!


i load JPEG images into BufferedImage objects and draw them using
Graphics2D.drawImage(...)

to be able to use LookupOp (for gamma and brightness adjustments) i
have to convert them to one of the following image types:
TYPE_INT_RGB or TYPE_INT_BGR.
the JPEG-native type TYPE_INT_3BGR doesn't work.

[ note: the conversion is done by creating an empty BufferedImage with
same size but different image type, and drawing the loaded image into
the newly created image: ]

BufferedImage img = ImageIO.read(new File(fileName));

BufferedImage temp;
temp = new BufferedImage(img.getWidth(), img.getHeight(),
BufferedImage.TYPE_INT_RGB // <-problem
);

temp.getGraphics().drawImage(img, 0, 0, null);
img = temp;


now the problem:
the images are drawn correctly, when using
TYPE_INT_BGR under linux but: TYPE_INT_RGB under windows.
so, when the 'wrong' type is used, the colors look ugly.

i tried to get to know the system-native image type by letting
GraphicConfiguration create a BufferedImage:

GraphicsEnvironment ge = GraphicsEnvironment
.getLocalGraphicsEnvironment();
GraphicsDevice gd = ge.getDefaultScreenDevice();
GraphicsConfiguration gc = gd.getDefaultConfiguration();
BufferedImage bestImage = gc.createCompatibleImage(1, 1);

but: on both systems bestImage.getType() equals TYPE_INT_RGB, so under
linux the colors are wrong.

i think that it is wrong to assume, that the linux platform always
implies TYPE_INT_BGR and the windows platform always implies
TYPE_INT_RGB.

so how can i get the real system-native image type?


thanks in advice!

 

[Knute Johnson]

hello!


i load JPEG images into BufferedImage objects and draw them using
Graphics2D.drawImage(...)

to be able to use LookupOp (for gamma and brightness adjustments) i
have to convert them to one of the following image types:
TYPE_INT_RGB or TYPE_INT_BGR.
the JPEG-native type TYPE_INT_3BGR doesn't work.

[ note: the conversion is done by creating an empty BufferedImage with
same size but different image type, and drawing the loaded image into
the newly created image: ]

BufferedImage img = ImageIO.read(new File(fileName));

BufferedImage temp;
temp = new BufferedImage(img.getWidth(), img.getHeight(),
BufferedImage.TYPE_INT_RGB // <-problem
);

temp.getGraphics().drawImage(img, 0, 0, null);
img = temp;


now the problem:
the images are drawn correctly, when using
TYPE_INT_BGR under linux but: TYPE_INT_RGB under windows.
so, when the 'wrong' type is used, the colors look ugly.

i tried to get to know the system-native image type by letting
GraphicConfiguration create a BufferedImage:

GraphicsEnvironment ge = GraphicsEnvironment
.getLocalGraphicsEnvironment();
GraphicsDevice gd = ge.getDefaultScreenDevice();
GraphicsConfiguration gc = gd.getDefaultConfiguration();
BufferedImage bestImage = gc.createCompatibleImage(1, 1);

but: on both systems bestImage.getType() equals TYPE_INT_RGB, so under
linux the colors are wrong.

i think that it is wrong to assume, that the linux platform always
implies TYPE_INT_BGR and the windows platform always implies
TYPE_INT_RGB.

so how can i get the real system-native image type?


thanks in advice!

Try the method below to convert your image to the type you want it to
be. This method converts to a compatible type but you can make it any
type you want.

// method to convert an image read from a file to a compatible image
BufferedImage convertImage(BufferedImage image) {
GraphicsEnvironment ge =
GraphicsEnvironment.getLocalGraphicsEnvironment();
GraphicsDevice[] devices = ge.getScreenDevices();
GraphicsConfiguration gc =
devices[Math.min(devices.length-1,0)].getDefaultConfiguration();

BufferedImage compatible gc.createCompatibleImage(image.getWidth(),
image.getHeight());

if (compatible.getType() == image.getType())
return image;

ColorConvertOp op = new ColorConvertOp(
image.getColorModel().getColorSpace(),
compatible.getColorModel().getColorSpace(), null);
op.filter(image, compatible);

return compatible;
}

 

[linuxadmin]

thank you very much, i'll try it out!