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Convert gray PNG to black and white TIF produces garbage output.

Jun 11, 2013 at 10:45 PM
I am new to ImageMagick (been using FreeImage) and I am trying to convert a bunch of grayscale PNG files to black and white (bi-tonal) tiffs. The code I have runs but produces tiffs that I can not open in anything, they are just garbage. Any help would be greatly appreciated. Here is what I got, it is C#:
public void convertPNGtoTiff(string workingFileName)
{
MagickImage PNGimage = new MagickImage(workingFileName);
PNGimage.QuantizeColorSpace = ColorSpace.GRAY;
PNGimage.QuantizeColors = 2;
PNGimage.QuantizeDither = true;
PNGimage.Quantize();
string newfilename = workingFileName.Substring(0, workingFileName.Length - 4) + ".tif";
PNGimage.Write(newfilename);
}
Coordinator
Jun 12, 2013 at 5:33 AM
I think you should use the extension 'tiff' instead of 'tif'.
Jun 12, 2013 at 7:23 PM
Thanks for the reply. That made the outputted file 4 times larger, which looks more like the expected size, but I still can not open it with anything.
Coordinator
Jun 12, 2013 at 7:27 PM
Would you mind sharing one of your images so i can try to reproduce your problem.
Jun 12, 2013 at 8:25 PM
No problem, how do I get it to you? Also, I have been hacking at this and I found that if I save the output as a PNG it works fine, something about the tiff conversion is messing it up. I have also tried setting IsMonochrome = ture, it works faster and outputs an even bigger file but it is still no good.
Coordinator
Jun 12, 2013 at 8:48 PM
Have you tried loading the image after saving it? You will get some information about the image with MagickImage.ToString(). Can you share the image with some public service like 'http://imgur.com/' or do you want to keep it private?
Jun 12, 2013 at 10:33 PM
I uploaded it to http://imgur.com/S2RrhOA
Coordinator
Jun 12, 2013 at 11:09 PM
Edited Jun 12, 2013 at 11:18 PM
I tried your code and I seem to get the correct result: http://imgur.com/v216mYg.

edit:
It seems that the tiff I uploaded got converted to a png. If you contact me through codeplex (from my profile page) I will receive an email. I can send you a reply that includes the tiff I created.
Jun 12, 2013 at 11:26 PM
Now that makes this harder. Any idea what else could be wrong? Would it be helpful for me to email you the bad output I get for the same image and see if you can make heads or tails of what it is? Thanks again for all the help.
Coordinator
Jun 13, 2013 at 2:29 PM
This discussion has been copied to a work item. Click here to go to the work item and continue the discussion.
Coordinator
Jun 13, 2013 at 2:41 PM
The problem was the tiff compression that is being used. I created an issue to add the property that can be used to set the CompressionType.