Re: Screenshots/PNG files in manuals

[David Kastrup]

"Phil Holmes" <address@hidden> writes:

> ----- Original Message ----- 
> From: "Phil Holmes" <address@hidden>
> To: "Devel" <address@hidden>
> Sent: Thursday, August 15, 2013 4:31 PM
> Subject: Screenshots/PNG files in manuals
>
>
>> As I said earlier, I'm working on the tutorial in the LM.  It uses
>> screenshots to show what users will see on the screen.  The versions
>> on the web are (as expected from a pixel-based system) fine.
>> However, the versions in the PDF docs are badly scaled and look
>> ugly.  It seems that this is generally tackled for images by making
>> them large and then constraining the width in the tex version of the
>> source (this is how it's done in the essay). I'm wondering if
>> there's a better way - is there a recommended pixel-per-inch setting
>> for image files that will end up in the PDFs?  I've looked on the
>> web and couldn't find anything, but am hoping someone will know.
>
> I resorted to generating a number of pixel-constrained grids at
> different PPI to try to work this out, and this is what I've found.
>
> The main problem with screenshot-type images in the PDFs is that the
> viewer program scales them badly on screen, and as a result they look
> bad.  Printed output is far better.  However, if the resolution of a
> screenshot is left at its default, then the image in the PDF is far
> too big.  In my experiments, it appears that a setting of 120 pixels
> per inch gives a good compromise between having an image large enough
> to be legible, and allowing images of a reasonable pixel count.

I don't actually understand what you are trying to say here.  A screen
shot should always have one pixel per pixel, anything else does not make
sense.  You want to use PNG.

> With 120 PPI, the maximum image size is just over 750 pixels.

The main problem is that you'll ultimately want the output to be
something like 100dpi or 150dpi in print.  _Exactly_ so.  So scaling to
a certain width is likely to be problematic.  You should figure out the
typical available width, pick a resolution, and then resize your window
to match the available width before doing the screen shot.  Then it's
best to specify the exact width when including the image, and center the
image in the available line width whatever it may be.

-- 
David Kastrup