8-bit graphic formats

[wolfgang]

Hi agraham
I’m not sure if this is really correct. A gif is not only a compressed format, it’s color reduced too. I tested this with IrfanView on PC. A 6 MB bmp takes 6 MB in Ram and the same as a gif only 2 MB. My PPC is a 65536 (16 bit) color system. When I load a bmp or a jpg file in my device it will be reduced from 24 bit to 16 bit and the gif will be expanded from 8 bit to 16 bit. This could be the reason for all my maps take the same memory. I’m not really sure but this seems to be an explanation.

[agraham]

Originally Posted by wolfgang

I’m not sure if this is really correct. A gif is not only a compressed format, it’s color reduced too.

There are several different sorts of memory bitmap format depending upon the colour depth of the image and whether its utilises a colour palette or not. Not surprisingly the desktop supports more formats than the device.

Maybe I misunderstood your post but the point I was making was that compression in the file does not translate to less memory when loaded. It is the image format of the picture that determines the memory used, not the type of file in which it is stored, although some file formats are restricted in the image formats they can accept.

As you have found out the Windows GDI+ graphics routines (a Drawer object)cannot handle palettised bitmaps - they have to be expanded to a minimum of a 24 bit colour bitmap in order to be manipulated so occupying more memory.