Screen captures and sizing

[Ian Hawkins]

Short answer?

Capturing with SnagIt, saving as PNG, and importing by reference are all 
good practices.

When you import into FrameMaker, use one of the following DPI settings, 
depending on the size of the image:
72
96
120
144
192

Longer answer?

To get the best results when viewing a screen capture in a PDF, the 
image should display at full size. That is, every dot (pixel) in the 
image should correspond to a single pixel on the computer monitor.

Acrobat and Adobe Reader use some default values for displaying images. 
For the most part, they assume that the monitor displays 96 pixels/inch. 
Yes, this is "fictional" as you point out, but it's still important. If 
I create a screen capture, import it into FrameMaker at 96 DPI, create a 
PDF, and display it in Adobe Reader at 100% zoom, the image will be 
perfect. It will be the same size as the original screen capture, and 
there will be no loss of quality. At any other zoom level the image will 
be degraded because there is no way to match the image pixels perfectly 
with monitor pixels.

When the original image is too large, you have to use a higher DPI. If 
you choose one of the values in the list above, you increase the chances 
that users will be able to find the right zoom level.
72 DPI matches a zoom level of 75%.
96 DPI matches 100%.
120 DPI matches 125%.
144 DPI matches 150%.
192 DPI matches 200%.

There are some caveats for this advice. Users can change their operating 
system defaults or Adobe Reader defaults so that 96 DPI is no longer the 
default value for displaying images. Most don't, though, so you can set 
up your PDFs for the majority.

HTH,
Ian


Spectrum Writing wrote:
> All,
>
>  
>
> I know that there are many graphics gurus on this list and I will be the
> first to admit - I am NOT a graphics guru and it is my weakest point. That
> said, I have never had any comments from clients until now about what I do
> for screen captures, and I wanted either confirmation or some additional
> insight on improvements for taking screen captures.
>
>  
>
> Here is the current comment from a client: Generally, I would like to keep
> high quality of screen captures. 
>
> Would like to suggest using a tool that can downscale the images with a
> smoothing function to keep high quality appearance. (as appear here, this is
> just sub-sampling with no smoothing.) 
>
>  
>
> I use SnagIt as my capture tool. I use the region option and capture either
> the relevant portion that I need or if required, I take a capture of the
> whole screen. I then save the capture as a .png, and use the import file
> function to bring the capture into my Framemaker file. Obviously, the
> default dpi is set to the fictitious Windows 96 dpi. I change the capture to
> 150 dpi and import. If this works for size and clarity, then I am done; if
> not, I right-click on the picture and adjust the dpi until I get the size
> that works for the page layout and what I am trying to show. (After much
> reading on this list, and advice from another colleague, I have learned that
> what I was initially taught at a long ago gig - to set the dpi to 300 and
> then use the manual sizing handles - is NOT the way to go).
>
>  
>
> Can any of you graphics gurus give me some insight as to what else I should
> be doing/changing or if I am doing it the right way - and if you want to
> lecture me off list about dpis and stuff, that is fine with me too. I will
> gladly take whatever information I can glean so that I can reply
> professionally and non-emotionally to this client about why the pictures
> are just fine for PDFs.
>
>  
>
> Thanks so much,
>
>  
>
> TVB
>
>  
>
> Tammy Van Boening
>
> Owner/Principal
>
> Spectrum Writing, LLC
>
> www.spectrumwritingllc.com <http://www.spectrumwritingllc.com/> 
>
>  
>
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