Schematics Archive (II)

[Geren W. Mortensen, Jr.]

>> >In my experience, the best scans of schematics have been 1 bit b/w, minimum
>> >300 dpi, preferrably 600 dpi.  This makes for a compact file, and if you're
>> >reproducing black line drawings on a white background, typical of most
>> >schematics, you shouldn't need anything else.
>>
>> Exactly, only a lot of the stuff I've seen is just as I described (24 bit
>> RGB). JPEG doesn't get rid of everything. Not only a longer download, but
>> the first thing I have to do is massage the image so it won't waste all
>> that space on my hard drive when it's uncompressed.
>
>    Personally I like 2-bit at 300dpi.  Not all stuff looks great in
> 1-bit, especially badly written text.  Heck there's scans which I've had
> to leave at 4-bit because of images and what-not.  And not all of us have
> access to 600 dpi printers anyway (go figure).
>
>> Another thing I've seen is stuff scanned at 72 DPI! I guess they figured it
>> would be too big otherwise. Looks like poorly anti-aliased smudgy text with
>> crappy drawings. Poor contrast, too. Lots of gray along the edges. Again,
>> they must not have much in the way of software, or no one's ever shown them
>> the right way.
>
>    Funny you should mention the dreaded 72 dpi... it seems like I should
> corner Adobe products for this one, but it seems like ANY image you open
> in Photoshop it defaults to 72 dpi, no matter how big your image is.
> Maybe it is some odd Windows thing, I don't know, but it sure is a drag
> to have to manually set it to 300 dpi.  :/
>    Obviously anyone who diliberately _scans_ in 72 dpi is just plain
> wonkers.  ;)

Not just a Windoze thing.  It happens on a Mac, too.  And not just with
Adobe products, on either platform.  As it turns out, screen resolution is
72dpi, so it defaults to the screen.

Regarding resolutions, I always scan at a minimum of 300dpi, but, depending
on the application of the final image, I'll drop resolution accordingly.
For instance, if I have an image that is only for viewing on screen or
video, I drop down to 72 dpi once I've finished working on the image.  If
something is destined for print, I'll change the resolution based on the
maximum lpi the target printer is capable of (an example, a 600 dpi HP
Laserjet 4M is capaple of about 70 lpi max while maintaining full gray-scale
reproduction).  If I'm printing an image under this circumstance, I'll set
my image resolution to 140 dpi, as any more simply creates a print job that
is large and slow.  The printer ends up wasting time on parts of the image
it can't even print.

Geren W Mortensen, Jr.

--
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