[Gimp-user] 8 and 1 bit images

[jgarnold <forums gimpusers com>]

> looking at this
>
> http://www.fsdeveloper.com/forum/threads/bland-mask-water-mask-how-to.18894/
> it says
>
> "quote" ...is the watermask. This gives water characteristics to any
> black area. The mask is an 8-bit tif using only black and white
>
> So that is all you need. A grayscale image. If your image has
> transparency (an alpha channel) remove it
>
> Layer -> Transparency -> Remove Alpha Channel
>
> export as as a tif

Thanks for your reply and advice.
Maybe it's a personal preference but the guy who was replying to my thread at
fsdeveloper.com suggested that I export the BLEND mask (layer where everything
the user doesn't want to show painted with a 25% BLACK brush so the edges are a
greyscale and blend nicely) as a 8bt 256 grayscale TIFF image and the water mask
which is painted with a 100% BLACK brush as a 1 bit 2 color (black and white)
TIFF.
I guess they both can be as small as possible although he also reckons the
'compile file' (which uses the original satellite image and the water and blend
mask image files) ends up smaller too. Once again just a preference of his to
have all files as small as possible.
I have in the past exported the mask/layer as a 24 bit BMP file and it all
worked ok. Of course the BMP files are much larger.

-- 
jgarnold (via www.gimpusers.com/forums)