A bug & note on using .png graphics....

[Art Campbell]

I think we're using slightly different terms when describing the same files.
In photos/photoshop, an 8-bit depth means 8 bits of red, green, and blue
info. 16 million shades (256X256X256). Which is what I think you're calling
24 bit, meaning 3x8 bits. Files come out of my Nikons at 12-bit depth and
are treated in Photoshop as 16-bit, which means millions more possible
colors.

Interpolated means resized or having the resolution adjusted in such a way
that the software supplies missing pixel data when necessary. When pixels
have to be dropped when an image shrinks or added when it is enlarged, an
interpolation routine is at work.

300 dpi for offset press work isn't excessive.

The color definition thing is really wierd. I never saw that happen before.
Odd that it only seems to be png. I can see it being useful though if you have
to color-match something in a layout to a graphic color, but it's
still really odd
that it'd pop up here. And it'd certainly add to file bloat.

Makes me wonder if the crash was happening because the number of colors
exceeded a maximum number in the file....

Art

On 5/4/06, Combs, Richard <richard.combs at polycom.com> wrote:
> Art Campbell wrote:
>
> > Color list? You mean like FM's defined colors?
> > I don't think so. We're talking digital photographs here,
> > with millions of colors.
> > The 8-bit limitation is just the bit depth of the file. FM
> > doesn't do anything at all with the colors of graphics and
> > the colors it defines.... it's a graphic file format attribute.
>
> Nope, not millions of colors -- millions of _possible_ colors. But each
> 8-bit graphic contains only 2^8, or 256, unique colors -- a palette of
> 256 defined RGB colors, all of which are added to your FM color list
> like this:
>
> RGB 000, 000, 136
> RGB 000, 082, 044
> RGB 056, 188, 000
>
> So Grant is right. Since each new 8-bit PNG contains its own palette of
> 256 unique colors, you can end up with hundreds -- even thousands -- of
> new colors in your FM doc. Go ahead, select View > Color > Definitions,
> and then look at the Name list.
>
> Since your graphics started life as photos, I'm surprised that the
> 256-color limit isn't a problem, but then I don't know what they're
> pictures of. I don't understand your original crash problem, or how the
> photos ended up being 16-bit color (are you sure?), or what
> "interpolated to size" means. But you might try saving them as 24-bit
> color, which is more standard. You might also try significantly reducing
> the dpi. I'm no expert, but 300 dpi for a photo seems excessive.
>
> IIRC, after you remove the 8-bit PNGs, saving the doc as MIF will get
> rid of all the RGB color definitions.
>
> Richard
>
>
> ------
> Richard G. Combs
> Senior Technical Writer
> Polycom, Inc.
> richardDOTcombs AT polycomDOTcom
> 303-223-5111
> ------
> rgcombs AT gmailDOTcom
> 303-777-0436
> ------
>
>
>
>
>


--
Art Campbell                                             art.campbell at gmail.com
  "... In my opinion, there's nothing in this world beats a '52 Vincent
               and a redheaded girl." -- Richard Thompson
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