[Ham-Computers] RE: Is Smaller Really Larger?

[Hsu, Aaron (NBC Universal)]

Hi Duane,

Sounds like it's a printer setting issue in the program you're using to print the scan.  Some programs keep the previous print settings.  Since you previously printed at 150dpi to match the 150dpi scan, the program may have kept the 150dpi print setting when you tried to print the 300dpi scan.  This would result in a print scaled by 2 - in other words, the print is now twice as large.  Why?  The program prints at 150dpi, as you requested, but there's actually 300dpi of data; therefore, to print the entire image, it requires twice the amount of print space.

Check the print dpi setting in the program you're using.  If the program doesn't allow dpi print adjustments, make sure the program is set to "scale" the photo to whatever actual print size you wish to print.  Most programs (photo or graphics editors) allow you to set the output size in inches (or pixels) and the program will shrink or expand the image to fit those dimensions.

Matching scan dpi with print dpi is a baffling situation for many people.  That's why companies such as HP don't use dpi as a descriptor in their programs.  Instead, the program asks "what kind of document are you scanning (or printing)?  The program then sets what dpi it thinks is best based on the type of document.  The same occurs when you print - the program asks "what size would you like?" and prints the document/image fitted to that size.  They're basically assuming that you chose the right document type when you scanned the document to get the right results.  For example, if you said that the image was for an e-mail, it would scan at 72 dpi.  However, if you try to print it to 8 x 10, it would look horrible.  But, it's still easier than teaching the average person about Dots Per Inch (dpi) and what scanner/printer settings to adjust.  It gets worse during the explaination of "true" dpi vs "interpolated" dpi.  I digress.


73,

  - Aaron Hsu, NN6O


-----Original Message-----
Sent: Wednesday, September 13, 2006 2:52 PM
Subject: [Ham-Computers] Is Smaller Really Larger?


Hello All,

I would greatly appreciate it if one of you would explain some object resolution puzzles to me. Some who are sighted, unlike myself, may benefit also. Thanks!

FYI: I was normally sighted until the eve of my eighteenth birthday when a careless Pheasant hunter shot me.

I have a printed document that measures 8W by 10H, portrait orientation. I scanned it at the default DPI of 150, quarter inch margins, both sides, top and bottom. It was scanned in color.  It was saved as a .jpg with no compression.

The image printed out fine. Correct margins, correct size.

I scanned the image a second time, but I increased the DPI to 300. I also used 5% compression.

This time the image was large enough that the last line of text was missing. 
It also pushed the margins out.

Here is where I am confused. When the number of dots in a given area increases, from 150 per inch to 300 per inch, the image quality, AKA resolution?, improves. Instead of making the image smaller, it made it larger. I thought that less dots per inch would make it larger with lower resolution, but it is working in reverse, or so it seems based on the description related to me.

What I want is a quarter inch border/margin, all the way around. The image should be 8X10. However, I can get along with a half inch border and smaller image. The image could be between 5X7 and 8X10, for instance.

I want the best detail I can get.

Since the image consists of four color photos and some text, I saved it as a .tif I also saved it as a .jpg for comparison.

The .tif is too large, for some reason.

How did I get the original image? My daughter used some version of Adobe and created it. She printed a copy with quarter inch margins. The file she gave me was the one Adobe writes with its own particular extension. Which fails to load into any software I have! Adobe I do not use for personal reasons.

Since I had the image on paper, I thought I could just scan it, size it to be an 8X10, save it to disc and print it. Which is exactly what I did. The problem arose when the higher resolution image did not fit the 8.5X11 paper I was using.

The scanned image at 150 DPI fit, but I thought I could improve the quality by doing what I have beeninstructed to do by those who know what they are doing when it comes to graphics. Namely, increase the DPI for scanning and the compress it down to fit.

Help!

What is the best way to get a good scan of this image and then print it on normal photo soft gloss paper stock of 8.5X11 without exceeding the margins and/or going off the page?

Duane W8DBF
dfischer at usol.com