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| Anybody wants old data books (UK)? |
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| Zero999:
--- Quote from: TerraHertz on April 30, 2022, 07:48:22 am --- --- Quote from: nctnico on April 28, 2022, 03:56:13 pm ---BTW: choosing a single level between black/white doesn't sound like a good solution. AFAIK there are better ways available nowadays that use a dynamic threshold to determine which parts are black / white. --- End quote --- That's not what I suggested. You're thinking of two-tone, ie fax mode, which is evil even for simple text. I meant, choose the upper and lower scan cutoff levels to give true white and black in areas that are supposed to be white and black. I say 'supposed to be' because on paper they never actually are, unless you're printing with vantablack and surface-of-the-Sun plasma. But the publisher's intent was pure white and black, so it's valid to assign ffffff and 000000 codes to those pixels. There still need to be gray levels between. Just how many levels, depends on the context. For black and white text, where all that's needed is to preserve visually clean curves on character edges, 16 levels (4 bits/pixel) total is adequate with sensible pixel sizing relative to the font. For B&W photos, at least 256 and preferably 64K levels to avoid visible posterization effects. For full colour, then 24 bit or better. But the main point is to remove visually insignificant noise in flat color areas, so PNG's RLL compression scheme can work best. Btw, 'dynamic threshold' can't work for multi-page documents. It will adapt differently on pages of different content, resulting in digital page representations that look different when they should be the same. You have to do trial scans of representative pages, then choose a scanning and post-processing profile that works best for all of them, then stick with that one profile through all the work. Unless there are radically different types of pages, in which case you need a profile for each type. --- End quote --- I agree wholeheartedly about PNG, rather than JPEG. For colour diagrams, it's often better to use a lower colour depth. 8-bit is often more than adequate. Regarding the original post: does anyone still use hard back? I find it inconvenient. The only advantage I can think of is, there's still a lot of books which are only available in traditional paper format. |
| nctnico:
--- Quote from: TerraHertz on April 30, 2022, 07:48:22 am --- --- Quote from: nctnico on April 28, 2022, 03:56:13 pm ---BTW: choosing a single level between black/white doesn't sound like a good solution. AFAIK there are better ways available nowadays that use a dynamic threshold to determine which parts are black / white. --- End quote --- That's not what I suggested. You're thinking of two-tone, ie fax mode, which is evil even for simple text. I meant, choose the upper and lower scan cutoff levels to give true white and black in areas that are supposed to be white and black. I say 'supposed to be' because on paper they never actually are, unless you're printing with vantablack and surface-of-the-Sun plasma. But the publisher's intent was pure white and black, so it's valid to assign ffffff and 000000 codes to those pixels. There still need to be gray levels between. Just how many levels, depends on the context. For black and white text, where all that's needed is to preserve visually clean curves on character edges, 16 levels (4 bits/pixel) total is adequate with sensible pixel sizing relative to the font. --- End quote --- Yes and no. IMHO you only need gray levels to make clean curves if your resolution is too low (and to me such text looks like blurred crap anyway). If your resolution is high enough (at least 300 real dpi) then you shouldn't need gray scale to show nice text. But again, this is only for the output format. Original 'master' scans are better made in color (using at least 300 real dpi) if you care about preservation. This way you can post-process the 'master scans' in whatever way you like using the latest technology in order to produce better a better result in an output format. From what I have seen so far, scanning software that comes with a scanner usually isn't very good at dealing with scanning text / black & white anyway; dedicated & more sophisticated software should be able to give much better results. |
| Stray Electron:
--- Quote from: tggzzz on April 28, 2022, 03:50:49 pm ---I scanned a 48 page scope service manual into a <8MB pdf file. It included photos, text, schematics, colour PCB layouts. That's too large to be attached here, but I've attached a similar one below. In my opinion it is just a legible as the original, unlike many you find in the repositories :( The basic workflow is dictated by what I found on a bog-standard linux box. No doubt there are better dedicated tools, but... The steps were: * scan at 300dpi, save as colour JPG file * use a shellscript to convert each page to two small TIFF files, one more suitable for photos, one for text/diagrams * for photos, optionally posterise it to reduce size * convert each TIFF file to a single-page PDF * concatenate all the PDF files to produce the single final file I previously tried simply including JPGs in a PDF file, but my tools compressed them so much they were unacceptable. Using TIFF files avoided that. --- End quote --- I work with a couple of Professional archivists and they save everything as TIFF. FWIW I've been looking at a new software package for saving image files of old documents called Vivid-pix and it looks VERY good. it's not a full blown editor like PhotoShop or GIMP and it doesn't clean up scratches and other damage but it does a VERY good job of automatically setting the white balance and contrast and it's fast and easy to use. The price is only $49 and you OWN it and it installs on your computer, not on the cloud. You can also download a limited use trial version for free. www.vivid-pix.com |
| tggzzz:
--- Quote from: Stray Electron on May 03, 2022, 01:18:53 pm --- --- Quote from: tggzzz on April 28, 2022, 03:50:49 pm ---I scanned a 48 page scope service manual into a <8MB pdf file. It included photos, text, schematics, colour PCB layouts. That's too large to be attached here, but I've attached a similar one below. In my opinion it is just a legible as the original, unlike many you find in the repositories :( The basic workflow is dictated by what I found on a bog-standard linux box. No doubt there are better dedicated tools, but... The steps were: * scan at 300dpi, save as colour JPG file * use a shellscript to convert each page to two small TIFF files, one more suitable for photos, one for text/diagrams * for photos, optionally posterise it to reduce size * convert each TIFF file to a single-page PDF * concatenate all the PDF files to produce the single final file I previously tried simply including JPGs in a PDF file, but my tools compressed them so much they were unacceptable. Using TIFF files avoided that. --- End quote --- I work with a couple of Professional archivists and they save everything as TIFF. --- End quote --- I've seen that with professional image libraries, since TIFF is essentially uncompressed. |
| tooki:
--- Quote from: tggzzz on May 03, 2022, 01:28:07 pm ---I've seen that with professional image libraries, since TIFF is essentially uncompressed. --- End quote --- That’s not correct. TIFF is a container format that can store one (or more!) images in numerous formats. It’s common for TIFF files to contain uncompressed bitmaps or use lossless compression (CCITT, LZW, ZIP, PackBits, and others.), and less common — but possible — for them to use lossy compression like JPEG, JBIG, and others. From my years of supporting clients in desktop publishing, it’s certainly fair to say that TIFF was almost exclusively used for uncompressed or lossless images, since there wasn’t any real advantage to using, for example, a JPEG-compressed TIFF over a native JPEG file. |
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