Mailinglist Archive: opensuse (908 mails)

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Re: [opensuse] apache 2.4 performance issue / processwire.
On 2016-06-08 16:23, Anton Aylward wrote:
On 06/08/2016 08:50 AM, Carlos E. R. wrote:
When I capture a computer display with png

If you mean use a screen-scraper tool like KSnapshot then no wonder you
get poor quality!

no no. A screen capture is by definition "maximum quality" always. It
has a defined number of pixels, it is a memory image. There is no
possible error.

However, rendering it as a jpeg is always lossy, by definition. Some
quality is lost, and you decide how much, in a compromise between
quality and size.

and then convert to jpg with
gimp (watching the quality-size balance)

OUCH again!
Gimp is not the best tool to do a png -> gif or jpeg conversion

No, gimp is the perfect tool to convert to jpeg (I didn't say gif).

Why? Because you can move the quality slider from 1 to 100 and watch the
result dynamically, instantly, and decide how much quality you want to
sacrifice. No other tool allows this.

Because of this human decision procedure, the result is slow. But perfect.

Try 'convert' from the ImageMagick package.

Not if you want to make the informed quality decision.

I observe that letters and
other details become grainy.

Its a shame that PNG doesn't define a 'text" chunk the way that HTML
does, or the other "XML" like standards such as SVG. NAPLPS, a sort-of
precursor to HTML in some ways was very text oriented and also had
'text' chunks.

Try DjVu, then. It renders letters precisely and with as much
compression as jpeg.

Cheers / Saludos,

Carlos E. R.
(from 13.1 x86_64 "Bottle" at Telcontar)

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