By: Kenneth - 18th February 2003 at 18:10
RE: Scanner test
I think it is an ex Swiss AF Pilatus P-2 with black crosses over the red/white Swiss insignia.
By: SADSACK - 18th February 2003 at 16:22
RE: Scanner test
Whats that German machine in the top picture, or rather what are the red rings behind the crosses?
By: geedee - 18th February 2003 at 14:51
RE: Scanner test
[updated:LAST EDITED ON 18-02-03 AT 03:13 PM (GMT)]Lets try again
nope, thats no better. Think I need to drop a few hints for a birthday pressie…like a decent scanner !
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By: Arabella-Cox - 18th February 2003 at 03:53
RE: Scanner test
[updated:LAST EDITED ON 18-02-03 AT 03:59 AM (GMT)]Quite impressive image.
I have a cheap scanner (Cannon LiDE 20) that scans 1200 x 600 in 42 bit. The 42 bit colour depth is a bit over the top. (The average human eye can only detect about 16.7 million colours which equates to about 24 bit (ie 2 to the power of 24) so 42 bit equates to 4,398,046,511,104 colours. If I am analysing an image for edge detection or running an recognition program this can be good or bad. (sometimes more information is better, sometimes its is just slower and bigger, sometimes it makes the image unusable for the task, though it is possible to reduce the colour depth in a meaningfull way, increasing colour depth synthetically introduces estimate or generated data which may ruin results.
I guess at the end of the day if you want to print an image go to the max of the scanner and software, but remember most printers can manage only 300dpi so any higher will not improve quality… it will just make it print bigger. If scanning text for OCR then 150dpi for clear text and perhaps up to 300 for not so clear. To post in the internet or to store on computer picture database then 72 dpi is fine (and easier to make small for easier transfers).
(Regarding file types, jpg is a very good compression format, though if the image has 4 or less colours in it… ie it is a diagram or black text on a white background with simple shapes like letters or arrows then gif format is often better. For printing a non compressed format is best as no detail is lost. Tif’s tend to be slightly smaller than BMPs and probably produce the best results.)
By: Snapper - 17th February 2003 at 18:47
RE: Scanner test
Indeed. You make very good points. My flatbed is a max optical resolution of 1600, and thats what I scan it at. An A4 sheet is quite large, but is then shrunk down to the 12″x8″ @ 300 (24.7mb in RGB, 8.24 in grayscale). Now, I print all my files onto real photographic paper, via the photolab I run. True c-type photo paper holds a resolution of 300 dpi, and these settings give me what I need up to 12″x18″ (the machines maximum). When I scan 35mm film, I do it in 48 bit at 4000 dpi. This gives me a huge file (thanks scsi!) which is immediately dropped to 24 bit before manipulating. Once that is done, its shrunk to the 24.7mb file that I use. If I want to upload it on here for example, I change it to 72 dpi, and a size of around 750 x 550 (ish) so that it fits on most monitors without scrolling. The monitor is not going to show the benefits of a 300 dpi file, and it would be very impractical. However, most of the files that I upload are clear, and printable, even from 100K files. And they still load quickly. Example was scanned from a 5×4 tranny on my Epson, in the manner described. I have printed it 12″ square at the lab, and it looks incredibly good.
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By: Arabella-Cox - 17th February 2003 at 01:04
RE: Scanner test
🙂
Obviously you’d need 4,000 dpi if the image is only 35mm across, but if you scanned an A4 sheet at 4,000 dpi you’d have a file measured in GBs not MBs.
For Photos I find using the max res of the scanner reduces colour depth and results in a lower quality image, of course it depends on the quality of your scanner.
At the end of the day any more than 24 bit colour cannot be perceived by the human eye and the screen resolution of most computers will display at 72dpi so any higher figures will not be noticed and just add to file size. (The difference between a 72 dpi image and a 150 dpi image on a computer screen is the area each takes up… ie the image’s physical size… not its quality onscreen.)
For printing unless you are getting it printed professionally 150dpi is about the limit of most printers and will result in adequate quality. (I have a friend who works in a printery and he says his biggest problems are with students who scan at maximum res… even if they are scanning printed text and they end up with images that need to be saved on Zip disk or CD-R when sensible resolutions could have kept it to floppy sized files. He has to spend time reducing the images, which they get charged for.)
By: Snapper - 16th February 2003 at 22:00
RE: Scanner test
I scan film at 4000 dpi on my 35mm scanner, and prints / medium and large format negs on my flatbed at 1600 dpi. I then resize to 12″x8″ at 300dpi as a tiff, then archive it. I drop to 72dpi, resize, and jpeg for the web. Scan big, shrink down – thats the best way to get the best image at a particular size. Why settle for crap if you don’t need to?
By: Arabella-Cox - 16th February 2003 at 21:15
RE: Scanner test
Unless I am printing the image I usually only scan at about 72 dpi anyway. The most important thing is to scan at max colour depth.
(When I scan to print I usually never scan at higher res than about 150 or 300 dpi… higher resolutions just make the files really big and slow to edit and don’t usually add that much information to the file… unless the thing being scanned has very high resolution like a photo.)
By: Kenneth - 16th February 2003 at 21:10
RE: Scanner test
Have you tried the sharpening filters in your photo editing software? All scans require some sort of sharpening afterwards (the sharpening function in the scan software is usually not sufficient!). I can recommend Adobe Photoshop Elements, which often comes free with the scanner, otherwise it is not that expensive. Use the “Unsharp Maskening” function. Be careful with too heavy compression of the picture size as it can result in jagged lines.
By: geedee - 16th February 2003 at 20:14
RE: Scanner test
Hey, thanks for the info.
Was beginning to think that it takes better piccies in monochrome !. I’ll have a play over the next few days and see how it goes.
Thanks again
Gary
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By: Snapper - 16th February 2003 at 18:12
RE: Scanner test
Geedee,
Scan in at the maximum optical resolution, then in a photo editing program (I use Adobe Photoshop) size the image to 72dpi and a width of around 750 pixels. Then save as a jpeg compressed to under 100 kb. Like this, it will be full screen-ish (without having to scroll along) and will show plenty of detail.
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February 16, 2003 at 5:28 pm
