Converting mixed image files

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BRuehl
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Joined: Tue Dec 17, 2019 3:27 pm

Converting mixed image files

Post by BRuehl » Tue Dec 17, 2019 3:35 pm

I have XnConvert Version 1.82
I am working on a project that involves images being written to film. I have a mixture of 1bit B&W Tiff. as well as 24bit Grayscale with LZW compression. In order for my machine to write to the film correctly I need 1bit B&W Tiff. only. What are the best filters to use and in which order should I use them to correctly convert these images?
What exactly does setting the "DPI" do within this program?

cday
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Re: Converting mixed image files

Post by cday » Tue Dec 17, 2019 4:13 pm

BRuehl wrote:
Tue Dec 17, 2019 3:35 pm
I have XnConvert Version 1.82
I am working on a project that involves images being written to film.
I have a mixture of 1bit B&W Tiff. as well as 24bit Grayscale with LZW compression. In order for my machine to write to the film correctly I need 1bit B&W Tiff. only. What are the best filters to use and in which order should I use them to correctly convert these images?
You need to convert the 24-bit TIFFs in a folder to 1-bit TIFFs, leaving existing 1-bit TIFFs in the same folder unchanged?

I think you can do that with XnConvert if you load the folder (or images in the folder) on the Input tab, on the Actions tab change the colour depth to 1-bit, and on the Output tab select the output format as TIFF with suitable compression for black and white such as LZW, or CCITT G4 which might produce smaller file sizes, both types of compression are lossless.

I think the existing 1-bit files in the folder will be unchanged, they should be opened and resaved unchanged, but always test with copies of files first! :wink: :wink:

What exactly does setting the "DPI" do within this program?
Changing the DPI of an existing image changes the canvas size, which is normally only a consideration when the image is printed, but might possibly be relevant when you write to film...

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XnTriq
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Re: Converting mixed image files

Post by XnTriq » Fri Dec 20, 2019 11:30 pm

Please keep in mind that it usually makes a big difference whether or not you're applying dithering during color reduction.

I recently had to convert a large batch of images to 1-bit color depth. In my case, libimagequant yielded the best results. Although available in XnView and XnConvert, the current implementation of this algorithm doesn't allow you to go lower than 8 colors or to turn off dithering, …

p159903.png
p159903.png (3.2 KiB) Viewed 730 times

… which is why I gave Pngyu a try. My workflow (screenshot of Pngyu used as example):
  1. Convert the TIFFs to PNG using XnConvert or XnView:
    p159903_1.png
  2. Reduce the color depth of the PNGs to 2 colors using Pngyu:
    p159903_2.png
    p159903_2.png (3.77 KiB) Viewed 732 times
  3. Convert PNGs to binary w/o dithering using XnConvert or XnView:
    p159903_3.png
    p159903_3.png (3.75 KiB) Viewed 732 times
Could you upload a sample of the files you're working with, BRuehl?

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