Re: images

[Jason Wynia <jwynia -at- AGRIS -dot- COM>]

> >What is the most effective method of creating/capturing images for
> >documentation in terms of high quality resolution and
> smallest amount of
> >disk space occupied?  I've experimented with differernt
> bitmap and tif
> >screen capture versions but would like to know if more efficient
> >alternatives exist, or alternatively, what the best of these is.
>
> Try using JPEGs (*.JPG).  It's a lossy compression, but the level of
> compression (and thus the quality) is adjustable.  At 75%
> quality, BMPs
> and TIFs can typically be cut down anywhere from 1/10th to 1/100th the
> file size.

The real answer to what is the best graphics format is "It Depends"TM. :)
Each graphic file format has different features which make it better for
different applications.  JPEG is best for photos, where for screen shots,
which are long blocks of similar colors GIF works better.  RLE compression,
which GIF (and other formats as well) uses basically have instructions for
the
graphic which say, "for this line, start with grey and use it for 400
pixels,
then use black for 3 pixels, then grey again for 300 pixels."  As a result,
this type of compression works well for screen shots, but not photos. This
makes
the files much smaller than straight TIF or BMP which record the exact color
information for each pixel instead.  In the example, TIF and BMP would have
color
information for 703 individual pixels, where GIF would have 3 color entries,
one
for each block.

Someone else covered the whole TIF and printing services angle.

Note:  this is not an exhaustive dissertation on graphics formats, and I am
not
even trying to make it 100% technically accurate.  Let's not even go into
the
difference between raster and vector.

Does anyone know of an existing FAQ on graphics formats for Tech Writers?
If not,
would there be interest in creating one?  I'll put it together if there is.

J Wynia

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