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Re: background-print

From: Mikko Rantalainen <mikko.rantalainen@peda.net>
Date: Fri, 12 Aug 2011 11:11:59 +0300
Message-ID: <4E44E04F.3050102@peda.net>
To: www-style@w3.org
2011-08-11 18:36 EEST: Tab Atkins Jr.:
> It's the color-adjustment that really clinches the fact that we can't
> solve this solely by fiddling with 'background'.  This really is a
> separate control with unique behavior, and has to be addressed with
> its own property (or some other entity, like an @-rule).  I still
> suggest:
> 
> printer-safe-colors: _prefer_ | avoid;
> 
> The "prefer" value biases the UA toward suppressing backgrounds and
> adjusting text colors so as to save ink.  The "avoid" value biases the
> UA against that.  The user still has the ultimate choice; this is just
> a suggestion, moreso than most other properties.

I find this property name and the suggested values to really hard to
understand (my mother language is Finnish).

As far as I understand, the intent for this property is to declare if
the content author has designed the color scheme to be sane for printing
on a normal paper using normal printer using normal inks (that is, the
less white the resulting page is, the more expensive the actual printing
is).

The name "printer-safe-colors" does sound more like "adjust the page
colors to fit in printer's gamut because this page contains wide gamut
colors" instead of "the UA should adjust colors to decrease ink usage"
(see "Perceptual rendering intent" below).

How about:

printer-colors: auto | economy | exact;
printer-colors: auto | economy | absolute | relative | perceptual |
saturation;

Here the values have following meanings:

auto: allow UA to decide (e.g. "economy" for normal printer, "exact" for
print to file, and in both cases include user override in print dialog)

economy: the UA should adjust page colors to minimize ink usage. The
resulting page rendering may use incorrect colors.

exact: the UA should trust the colors specified in by the CSS (computed
value after normal cascading of UA, author and user style sheets).

absolute: similar to exact but with additional knowledge that if color
management is used, "Absolute colorimetric" rendering intent should be used.

relative: similar to exact but with additional knowledge that if color
management is used, "Relative colorimetric" rendering intent should be used.

perceptual: similar to exact but with additional knowledge that if color
management is used, "Perceptual" rendering intent should be used.

saturation: similar to exact but with additional knowledge that if color
management is used, "Saturation" rendering intent should be used.

If you're not familiar with rendering intents, here's pretty good
summary for real world usage:
http://blog.lexjet.com/2010/12/20/how-to-find-the-right-rendering-intent/

And here's a pretty readable introduction about what really happens:
http://www.signindustry.com/digital/articles/2007-05-01-SGIA-Shell-RenderingIntents.php3

I think I'd prefer the second variant (with no "exact" but with direct
control of rendering intents). This is because the rendering intent
really should depend on the content of the document, not on printer type
or quality. Of course, if the intent is to save ink ("economy") then the
color quality is of no issue. Technically "exact" should mean "Absolute
colorimetric" but the result is seldom what the user wants even if used
had correctly color managed and calibrated equipment.

In the end, it might make sense to use following property:

color-management: auto | economy | absolute | relative | perceptual |
saturation;

This is because color management is not special only to printing (for
example, the "economy" value would make sense even for screen usage in
case of mobile AMOLED displays where using darker colors will conserve
battery).

-- 
Mikko
Received on Friday, 12 August 2011 09:03:04 GMT

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