by cncdrive » Sat Mar 31, 2018 3:02 pm
No pixel perfect show of the image is probably because the client area has different dimensions than what you think is.
Gerry gave a good idea to printscreen and measure the pixels count.
The minor color difference can be due to the image compression which depends on the particular video card's supported compression method and so the algorithm the UCCNC can use via OpenGL.
Remember that OpenGL is just a recommendation, but how it is implemented by different graphics card vendors on different graphics card is a different thing.
What the UCCNC do is it checks what compression methods are available with asking the graphics card and then using one of these methods in the order of how I typed them:
GL_COMPRESSED_RGBA_S3TC_DXT3_EXT
GL_COMPRESSED_RGBA_S3TC_DXT5_EXT
GL_COMPRESSED_RGBA
GL_RGBA
The last method is no compression, it is used if no compression is available on the card.
And the before the last is the default compression method of the card if the first 2 methods are not available.
So, depending on what the card supports and how that method is implemented there may be some minor color differences.