[Ham-Computers] RE: Photo Image Size Problem (long reply)

[Hsu, Aaron]

I'm usually hesitant to respond to scanner related questions as there are
too many variables involved!  But, here's my 2 cents...

You didn't mention what scanner or scanner software you're using, so I'll go
on "generics".

Different scanner software use different terms for their settings.  For
example, the older HP software didn't have a place where you could easily
just set dpi - you had to choose a template (such as "color photo") which
was defined with the dpi.  In these cases, to manually select a dpi setting,
you would need to change the "color photo" template or create a new
template.  Other sofware, like MagicScan for my UMAX PowerLook III scanner
or CanoScan for the simple Canon 670U scanner have a pull-down option to
specify the dpi.  Some software have both templates and manual settings.

Unfortunately, when using scanning software the uses templates, it possible
that the template has other settings that will affect how the scanned image
will be saved.  With this in mind, there might be a setting in the template
that's affecting the saved image.  Here's question...does the picture show
up properly in a different image viewing program?  If you don't have such a
program, a *GREAT* free one is IrfanView.  You can get it at
http://www.irfanview.com.  If the scan doesn't show properly in the other
viewing program, then the scanned image itself wasn't saved properly by the
scanner software.

Also, some scanner software don't properly set the dpi field in the saved
file (there's a header field for this in many picture file formats such as
.TIF, .JPG, etc.).  My Nikon CP-4500 digital camera sets this field to 72dpi
even though I think it should be set to 300dpi.  Why does this make a
difference?  If this field is set to something different than the "final
destination" of the photo (such as printed vs on-screen), then the program
opening the picture may scale it differently when the file is opened.  In
the past, I had problems with some graphics editors where if I opened a file
that's 640x480 in size, it would read the 72dpi setting and scale the final
destination as the computer monitor.  If I printed this picture, it would
print a (roughly) 2 inch by 1.25 inch "speck" as it only sent 72 actual dots
per inch (and the printer is expecting 300 dpi).  In Photoshop, I still need
to "resize" the pictures from my CP-4500 to 300dpi before I print it -
otherwise, I get the wrong printed size or I get "blocky" pictures.

For example, take a 2 megapixel camera.  That produces a picture that
1600x1200 in size.  At 300dpi printing, that's about 5.3" by 4", a decent
sized photo.  At 96dpi (typical comuter monitor resolution), that produces a
viewable picture that's larger than most monitors can show at once (well,
just the 1600x1200 resolution should clue one in there).  If you were to
scale down the picture to 800x600, the picture would then fit most monitors,
but the printed result at 300dpi would be 2.6" by 2", tiny.  And, if you
tried to scale that 800x600 to print at 300dpi, it would come out "blocky".

Here's a analogy.  Standard broadcast TV is about 352x240 in size.  However,
it looks great on a standard TV set as the TV is designed for this
resolution.  However, if you take the same 352x240 video and play it back on
a hi-res computer monitor, it looks either A) full size, but crappy and
blocky, or B) good picture, but tiny.  It's really more complicated than
this, but I think you get the general idea.

I'm wondering if Corel Draw 5.0 is scaling the picture to fit the page based
on fitting the width of the paper.  Remember, most printers *require* a
margin of .xx inches and therefore can't fit a full 8" scan.  Maybe Corel is
scaling the picture to fit the printer and the scaling is not keeping the
"aspect ratio".  When scaling/resizing images, it's important to check the
"aspect ratio" box to insure that if the image is reduced X% vertically,
it's also being reduced X% horizontally.  Corel might be printing the page
and scaling without keeping the aspect ratio.

There are a *LOT* more nit-picky things about scanning, images, .JPG, etc.,
but I'll stop here.  Just check to see what the dpi setting of the file is.
Also see if a different image viewing/printing program shows (and prints)
the picture properly (IrfanView also prints and has several print scaling
options).  And, check to see if Corel is set to keep the aspect ratio if
image is scaled to fit a printed page.

On a side note, setting compression levels in .JPG formats can be confusing.
Some programs ask for a "quality" level and other programs ask for the
"compression" level when saving .JPG's.  Obviously, both of these are
mutually opposite.  The highest "quality" level setting will result in the
lowest "compression" setting and vice-versa.  Remember that .JPG is a
"lossy" format, so the more compression, the worse the picture looks the
next time you open it.  And, if you re-save the picture, you'll lose more
info as it re-compresses the image again.  If you plan on saving scanned
images, it's best to use a "lossless" format such as .TIF, .PSD (Photoshop),
etc.  Yes, the resulting file is larger, but the resulting quality is *MUCH*
better.  If one insists on using .JPG to save space, then it's best to scan
the image at a higher DPI and use a higher compression level when saving as
opposed to doing a low-dpi scan with any compression level.  The resulting
filesize from both formats (high-dpi/high-compresion vs
low-dpi/any-compression) will be roughly identical, but the high-dpi file
will look (and print) *MUCH* better.  For my .JPG scans, I usually scan at
300dpi (or 600dpi) and use roughly 70% compression level (quality setting 4
in Photoshop).  The resulting files are viewable without blocky "aliasing"
and also look good when printed.  For archival scans, I use .TIF with LZW
lossless compression.

But, as usual, I digress.  If you have further Q's, feel free to ask!

  - Aaron, NN6O


p.s.  BTW, glad to see you're still with us Duane!


-----Original Message-----
From: Duane Fischer, W8DBF [mailto:dfischer@usol.com]
Sent: Wednesday, November 05, 2003 7:29 PM
Subject: [Ham-Computers] Photo Image Size Problem

	
I hate to repeat a post, but I received no reply. Now one of you wizards
surely
has an answer to this.	
	
I scan an 8X10 color print at 150 pi, scanner set to 'actual size' and saved
to
an image file. When finished, I select .jpg, the default is .bmp, and leave
it
at the default of 100% compression. I save it to a zip disk. 	
	
I load the image into Corel Draw 5.0 on my Windows 98 system. I do not
change
any default settings. I simply select print and press enter. 	
	
Now the picture that prints out is eight inches wide, but a fraction under
seven
inches high, not ten inches. The entire image is there. Why is it the wrong
size? How do I correct this? 	
	
Thank you. 	
	
Duane Fischer, W8DBF  	
dfischer@usol.com	



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