[Ham-Computers] FW: Re How Do You Scan?

Tue May 3 21:45:53 EDT 2005

Aaron always gives good advice. I might add that a medium to high speed computer and lots of ram (512 +) helps alot. Disconnect from the internet, close all programs and disable your anti virus while scanning will speed up the process. I find running scandisk (Chkdsk /f) and defrag before you scan speeds up the process. Spyware really sucks up performance also. Clean those cookies too.

-------------- Original message -------------- 

> There are actually two different issues here that need to be handled 
> separately - how to scan the document (what settings to use), and, how 
> should it be saved (file format and compression). For most scanning tasks, 
> one simple question can address both issues: 
> 
> "What is the final destination/purpose for this scan?" 
> 
> For example, is it going to be printed? E-mail? Archive? 
> 
> 
> 
> How to scan: 
> ------------ 
> 
> If the final destination is "print", then you should *always* scan at 300dpi 
> or higher...depends on content and especially if enlarging. I've seen many 
> instructions that state 150dpi is fine for color photos, but every 150dpi 
> print I've seen looks like crap. 
> 
> If the final destination is for archival purposes (e.g. preserving 
> documents), then scan at 300dpi or higher. Some suggest at least 600dpi or 
> even 1200dpi and saving in TIF format (more on TIF below). 
> 
> If the final destination is for viewing on a monitor (such as e-mail or a 
> screensaver/background image), then 72dpi or 96dpi will be just fine. The 
> reason is that monitors are 72 or 96dpi devices. Once you've scanned it, 
> re-size it to fit the screen - 800x600 is good for e-mails. Prints at this 
> dpi will generally look like crap (unless you print them "thumbnail" sized) 
> 
> One last thing...don't scan any higher than the true "optical" resolution of 
> your scanner. Most scanners these days are 600 or 1200dpi optical, but are 
> marketed as 4800 or 9600dpi scanners - the scanner just "interpolates" (aka 
> "adds") the extra pixels. Besides, most people will never need to scan past 
> 600dpi. 
> 
> 
> 
> How to save: 
> ------------ 
> 
> For typical use, JPG's at 4:1 compression is a good compromise between 
> filesize and quality. 4:1 is typically the "fine" mode on most digital 
> cameras and roughly equates to a "12" or "maximum quality" in Photoshop's 
> JPG save dialog. This should also be equivalent to about 95% - 100% 
> "quality" or "minimum compression" in other graphics programs. For example, 
> a 17MB "RAW" file reduced to a 2.5MB JPG using the "12" setting in 
> Photoshop. The resulting print quality is virtually indistinguishable 
> except by enlarging or those with good eyes. If the quality isn't that 
> critical (such as for e-mails), you can go down to 75% quality ("basic" mode 
> on many cameras) with good results and lower file sizes. With very high dpi 
> scans (600+), you can even go down to 50% and not see much loss of detail as 
> you've increased the number of actual pixels scanned. 
> 
> For critical or archival purposes, TIF is the universally accepted format. 
> If you use Photoshop, PSD is also good. The resulting file is large as it's 
> uncompressed, but you won't lose any detail unlike "lossy" compression 
> formats like JPG. Yes, there is LZW compression available in TIF, but it's 
> not quite standard and some programs won't recognize an LZW compressed TIF. 
> 
> Remember that these file formats are "graphics" files and not editable 
> documents. If you wish to scan a document and make it editable, you'll need 
> an Optical Character Recognition program like OmniPage Pro that takes the 
> content on the page and converts it back to an editable format (like 
> Microsoft Word). Basic OCR programs only work with printed text...sorry, 
> won't work with handwriting. 
> 
> 
> 
> So, Duane, if you're scanning "to print", try scanning at 300dpi and saving 
> as a 90% "quality" JPG (minimal compression). If it's for e-mail, scan at 
> 72 or 96 dpi and save as a 75% JPG. Don't forget to re-size to 800x600 for 
> e-mail! 
> 
> 
> 73, 
> 
> - Aaron Hsu, NN6O (ex-KD6DAE) 
> {nn6o}@arrl.net 
> {athsu}@nbcuni.com 
> No-QRO Int'l #1,000,006 
> . -..- - .-. .- ".... . .- ...- -.--" 
> 
> 
> -----Original Message----- 
> From: ham-computers-bounces at mailman.qth.net 
> [mailto:ham-computers-bounces at mailman.qth.net] On Behalf Of Duane B. 
> Fischer, W8DBF 
> 
> Sent: Tuesday, May 03, 2005 11:40 AM 
> To: ham-computers at mailman.qth.net 
> Subject: [Ham-Computers] Re How Do You Scan? 
> 
> 
> 
> 
> 
> Hello All, 
> 
> I have been told several different ways of scanning a document that contains 
> 
> color photos that form the top and bottom borders with text between them. 
> 
> 
> There are three headings, in various fonts and in different colors. 
> 
> I am scanning it at the default resolution of 150 PI, in color, to an image 
> file. This results in a .bmp file. I then save it as a .jpg with 10% 
> 
> compression. 
> 
> The results vary, none are acceptable. (from missing colr to missing text to 
> being off center to having the bottom edge missing.) What is the 'correct' 
> 
> method to scan a document such as I have described above? 
> 
> Thank you. 
> 
> Duane Fischer, W8DBF 
> dfischer at usol.com 
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