Cannot reduce to 256 colours

[terrypin]

One of my mapping applications (Memory Map) requires map images to be TIF with 256 or 16 colours, CMYK not RGB, to allow calibration. Until now I've had no trouble doing this from various maps, using Reduce Colour Depth, but I've now hit some sort of snag. I loaded a black and white map, or maybe including some grey. It was just a border around the UK, with dotted lines separating Wales and Scotland. Then I filled it with a light colour (used several, all with similar result). I reduced colour depth as usual. Checking showed it had 17 colours. But when I tried to save it, PSP8 displayed a message that because of the requirements it would be saved with 16 million.

What is going on here please?

Terry, East Grinstead, UK

[hartpaul]

Have just tested that with PSP 8 (not X8) and the message I get is "because of the limitations ... no EXIF information will be saved

[terrypin]

Thanks, appreciate the fast reply.

I get this:




Could you try it with my image please?
https://dl.dropboxusercontent.com/u/401 ... zzle-1.tif

And in case it helps, here's what I see in the TIF options:



--
Terry, East Grinstead, UK

[LeviFiction]

Have you tested different compression options to see if it still does the same?

[terrypin]

Have you tested different compression options to see if it still does the same?

No, as I'd seen that 'Packbits' option in previous successful saves.

But I think I may have been mistaken about the CMYK option. When I initially read the instructions "Scan or download the map image and save it as a 4 or 8 bit indexed color (16 or 256 color) TIFF or PNG format image. A full color RGB image cannot be used. The map should be free from distortion and discontinuities," I took that to mean it shouldn't be RGB. But now I think that was wrong and it should be RGB. Selecting that instead of CMYK gave no warning message. I'll try calibrating it asap to see if it's OK. Meanwhile, opening an earlier successful one (which I'd made in IrfanView), I see that has the RGB option selected, which reinforces my conclusion.

[JoeB]

I agree that you mis-interpreted the instructions. It doesn't seem as if you can save as CMYK color profile with a 16 or 256 indexed palette. Perhaps Google would be able to answer why not.