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Thread ID: 65366	2006-01-15 20:28:00	Irregular dots in scanned image	Lizard (2409)	Press F1

Post ID	Timestamp	Content	User
421401	2006-01-15 20:28:00	Hi everyone, I've done a few scans with the new multifunction we got for xmas, but have noticed that some of the pictures, most noticeably on colour pictures, there are white dots appearing in random places. They are irregular in shape, and can range from very small to very noticeable - they appear on the image to resemble dandruff, and don't turn up in the same places when repeated scans are done. It's more noticeable on screen in higher magnification, but when printed at 6 x 4in it's hardly noticeable but still visible. I'm sure they would be more visible if printed on a larger scale. I've tried cleaning the platen glass with a lint-free cloth (though no liquid cleaner as yet), and the dots still appear. I've tried cleaning the photos, but the dots still appear. I tried both these because it seemed the most obvious problem would be dust on the glass or picture, but now I'm thinking it could be dust under the glass. However this still isn't quite right as the dots don't appear in the same place every time, which suggests that it might be on the scanner bar itself, but not being overly familiar with the technology, I'm not sure of this. Does anyone have any ideas on what I could try next? Device is an HP PS2575 All-in-One PSC - brand new, out of the box less than a month. Using bundled HP Solution Centre and Image Zone software. Win XP, 1GB RAM, etc etc. Cheers Lizard	Lizard (2409)
421402	2006-01-15 20:42:00	"White" represents the maximum value for a pixel. If it was random garbage, I suggest that somehow you're getting a memory leak, usally a bad driver. There are very rare viruses that use images to store packets, but again it would appear as random garbage, not white. I don't know.	kingdragonfly (309)
421403	2006-01-15 20:56:00	Thanks kingdragonfly, that's a good suggestion. When you say memory leak, are you referrign to the printer's or the computer's memory? I"ve recently replaced the computer's 512MB RAM module with a 1GB RAM module, which fixed a number of problems such as random crashing (though there has been frequent frame-rate slow-downs in NFS:Most Wanted recently, but I put it down to the (possibly) under-powered gfx card (128 MB 9800 pro). Lizard	Lizard (2409)
421404	2006-01-15 21:25:00	Though I doubt it's faulty RAM in your PC, you may want to use a free downloadable utility called memtest86. It creates a bootable CD. http://www.memtest86.com/ I assuming your anti-virus is up-to-date, and you've scanned your PC recently.	kingdragonfly (309)
421405	2006-01-16 22:07:00	Though I doubt it's faulty RAM in your PC, you may want to use a free downloadable utility called memtest86. It creates a bootable CD. http://www.memtest86.com/ I assuming your anti-virus is up-to-date, and you've scanned your PC recently. I ran Memtest86 overnight, and after 13 passes, it found precisely 0 errors, so the RAM seems to be fine by that test. AVG detected a number of infected files a few days ago, and a few more last night. They're safely locked up in the virus vault. One thing I may try is saving the files as TIFF instead of JPEG. IS this likely to make a difference? Cheers Lizard	Lizard (2409)
421406	2006-01-16 22:27:00	I suspect you know this already, but here goes: TIFF is a lossless algorithms, meaning that no information is thrown away when you save it. TIFF file sizes are big, but it's a good format for editing, but not for posting or emailing.(TIFF lossy was proposed, but never implemented.) JPEG is a lossy algorithm, meaning information is discarded whenever it's saved. Depending on the quality and number of iterations, this may or may not be noticed. JPEG will usually be a smaller file size than TIFF, more so for photographs. For line-art, depending on the TIFF compression algorithm, TIFF might be smaller, but it's usually not the case. JPEG, GIF, and to a lesser extent PNG are the most common format for posting to the web. Personally I use PSD to save and edit files, Photoshop's, and then when I'm happy save it as a JPEG or GIF.	kingdragonfly (309)
421407	2006-01-16 22:42:00	You say you cleaned the platen glass, did you also clean the document cover?, crap on the cover will transfer to the platen glass when lowered with no document inserted. ?hence erratic dot location.	FrankS (257)
421408	2006-01-16 23:00:00	Not sure about the settings but did you use half tone or differing stuff like that? Some of those can be more pixelated. But by all means try it with TIF format. Any flatbed scanners quality wise don't expect to print it larger than 2x. Scan the film or use a digital camera.	Nomad (952)
421409	2006-01-16 23:01:00	I suspect you know this already, but here goes: TIFF is a lossless algorithms, meaning that no information is thrown away when you save it . TIFF file sizes are big, but it's a good format for editing, but not for posting or emailing . (TIFF lossy was proposed, but never implemented . ) JPEG is a lossy algorithm, meaning information is discarded whenever it's saved . Depending on the quality and number of iterations, this may or may not be noticed . JPEG will usually be a smaller file size than TIFF, more so for photographs . For line-art, depending on the TIFF compression algorithm, TIFF might be smaller, but it's usually not the case . JPEG, GIF, and to a lesser extent PNG are the most common format for posting to the web . Personally I use PSD to save and edit files, Photoshop's, and then when I'm happy save it as a JPEG or GIF . Thanks for the explanation - I had a vague idea that TIFF was lossless, but your explanation helped . I have a number of photos to scan, for archiving purposes . They may potentially be edited at some point in the future, but mainly I want to ensure good photo reproductions in the event that the original is destroyed . I was scanning at 600dpi, producing files just under a meg each in size . Cheers Lizard	Lizard (2409)
421410	2006-01-16 23:03:00	You say you cleaned the platen glass, did you also clean the document cover?, crap on the cover will transfer to the platen glass when lowered with no document inserted. ?hence erratic dot location. Yep, I cleaned both. But the dots were still appearing even though I would scan the picture, then remove the picture and clean the glass (without lowering the document cover), and then reposition the picture. Lizard	Lizard (2409)
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