[Gimp-user] 8 and 1 bit images

[jgarnold <forums gimpusers com>]

> Hate this mailing list format.
>
> Attached the wrong image. However it does demonstrate that not all
> applications will show transparency.
>
> screenshot of properties attached

The mask files needed are exactly what you state - the 'white' area is
'transparent' so when the original image (actually a satellite image of an area
in the world) is 'compiled' together with the mask file the black area is
interpreted as that part of the original image you want NOT included and the
white area allows the corresponding area of the original image to 'show
through'.
I have attached the original satellite image and the 'water mask'. The black
area in the water mask will result in all that part of the original satellite
image being masked OUT and the white area will allow that part of the original
satellite image to show through.
Hope I have explained properly.
Apart from an obvious smaller TIFF file (1 bit) it apparently results in the
compiled image file (a file type BGL which is used with Flight Simulator) also
being smaller.
I guess it's just to make smaller files.
I must get back to the 'scenery forum' and ask some questions.

Attachments:
* http://www.gimpusers.com/system/attachments/695/original/SECHELT_WEST_COAST_3_-_small.jpg
* http://www.gimpusers.com/system/attachments/696/original/SECHELT_WEST_COAST_3_water_mask_SMALL.jpg

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