Convert grayscale .pdf to black and white (big multi-page files) - Adobe Acrobat

This is a discussion on Convert grayscale .pdf to black and white (big multi-page files) - Adobe Acrobat ; Seems one of my employees inadvertently changed the scanner settings on one of our office scanners and scanned hundreds of files at 600x600 dpi, grayscale, instead of 300x300dpi, black and white. This resulted in eating up nearly 100 gigabytes of ...

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Convert grayscale .pdf to black and white (big multi-page files)

  1. Default Convert grayscale .pdf to black and white (big multi-page files)

    Seems one of my employees inadvertently changed the scanner settings on one of our office scanners and scanned hundreds of files at 600x600 dpi, grayscale, instead of 300x300dpi, black and white. This resulted in eating up nearly 100 gigabytes of server space, instead of about 10.

    Many of the individual files have 100+ pages in them and are consequently 100 to 200 megaybtes each.

    I am wondering of a way to convert them to the correct specs and reduce the file size.

    I've tried to run them through the Acrobat Distiller again, but due to sheer file size, it takes forever or hangs up the PC.

    Any aftermarket applications that can convert and reduce file size? Preferably in a batch process?

    Thanks.

    Karl

  2. Default Re: Convert grayscale .pdf to black and white(big multi-page files)

    What version of Acrobat do you have?

  3. Default Re: Convert grayscale .pdf to black and white(big multi-page files)

    I should add that everything is scanned as an image. No OCR is required.

  4. Default Re: Convert grayscale .pdf to black and white(big multi-page files)

    I have two machines. One running 5.0 and the other 7.0

  5. Default Re: Convert grayscale .pdf to black and white(big multi-page files)

    You can reduce the file size using PDF Optimizer in Acrobat 7, but I don't believe you will be able to convert from grayscale to bitmap.

  6. Default Re: Convert grayscale .pdf to black and white(big multi-page files)

    You may have to save as a TIFF or other graphic format and make the changes in a graphics program. With the volume, this may not be the best solution. All that I have ever been able to do in conversion is to gray scale. In AA7, this is done with the TOOLS>PRINT options. You may be able to play with the colors to get close to B&W, but I am not sure. In AA5, I used to print and select B&W in the

    Here are some results of a JPG conversion (all in AA7):
    1. Jpg opened and saved in AA7 - 143 kB
    : 718X1035 pixels full page, 8 bit color, RGB
    2. file converted to Gray scale - 224 kB
    : 718X1035 pixels full page, 8 bit color, Black
    3. Gray scaled printed to Adobe PDF printer with B&W/300dpi - 98 kB
    : 718X1035 pixels full page, 8 bit color, Black
    4. Color printed to PDF with B&W/300dpi - Totally black page (20 kB)
    5. (1) reduced by Reduce File Size - 15 kB, but pixels show.
    : 180X259 pixels full page, 8 bit color

    There is not a B&W option in the TOOLS section, just Gray Scale. However, you can change the convert to Map to Black Process. That gives another result listed below:

    6. Gray scale converted as Map to Black - 81 kB
    : 718X1035 pixels full page, 8 bit color, Black

    It looks like this last option might be your best chance of accomplishing what you want. I suggest you use extract pages (to new file) to get a few pages to work on. Then play on doing conversions. Basically, what I have just done. I am not sure you will get the 10:1 reduction you want, but you should be able to improve on the result. It might also be a good idea to break the document into chapters or some related form and have links to each.

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