Re: [Gimp-print-devel] Stylus photo 870

[Jean-Marc V. <ver...@if...>]

On May 2,  7:58pm, Robert L Krawitz wrote:

> Welcome!

Thanks

>
>    { 0.152, 0x1, 0 },
>    { 0.255, 0x2, 0 },
>    { 0.38,  0x3, 0 },
>    { 0.5,   0x1, 1 },
>    { 0.67,  0x2, 1 },
>    { 1.0,   0x3, 1 }
>
>    The last 3 values also go for K and Y (simple case).
>
> Well, this is easy to fix.  Thank you for doing this.  Would you like
> to commit the fix?

Sure if it's also applicable to other printers.

> The balance between light and dark inks is very different from what I've
> come up with; I came up with .25.  It might be that I'm using
> different inks, or they might simply be reformulated.

I just went back to what I had found for 3.1.2 and it was also between 0.35
and 0.4. 0.25 is definitely too low for me; 0.33 already is (too low).

>
> Could someone test these on a 740 and a 900 (standard_dither_ranges
> and dot_sizes also needs to be fixed the same way)?
>
>    On my STP870, my values yield absolutely identical densities for each of
the
>    inks/levels. The color balance still needs to be improved.
>
> What's wrong?  Maybe I can make some suggestions.
>
Primarily, red looks too yellow and blue too magenta to me. Gray is not quite
gray either. This can probably be fixed by adjusting the respective densities
but I haven't tried yet.

>    If I understand well, this should therefore apply as well to
print-escp2.c:
>
>    1217,1218c1217,1218
>    <         dither_set_c_ranges(dither, 5, variable_dither_ranges,
v->density);
>    <         dither_set_m_ranges(dither, 5, variable_dither_ranges,
v->density);
>    ---
>    >         dither_set_c_ranges(dither, 6, variable_dither_ranges,
v->density);
>    >         dither_set_m_ranges(dither, 6, variable_dither_ranges,
v->density);
>
> Indeed it should.
>
>    Finally as of the version before today's black was too dark.
>
> Let us know how the version as of this morning works, since that was
> one of the key improvements.  Maybe we can also try lower black
> thresholds (particularly k_lower) with the variable dot sizes.
>

Wow, much better ! I can see color again :) The thresholds look excellent.
Looks a bit grainy (Dither=2), but that's photo quality again.

By the way, I'm not using the gimp here, but ghostscript.


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Jean-Marc Verbavatz		<ver...@if...>
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