Legacy ImageMagick Discussions Archive

Hello,

I have a 2 part question.

1) I need to convert large tiff images (28MB) so that the Photometric Interpretation converts from min-is-while to min-is-black. This works nicely by just issuing convert file1.tiff to file2.tiff in my case - not sure why, but it doesn't matter. I need to create a script which gets these images from print spool directories on one UNIX (server server 1), convert and print these images on another server 2 NFS mounted to server 1. The issue is there are 6 or 7 different spool directories which indicate which printer to use, so in the convert process, I need to print to the correct printer on server 2. I have no issue in scripting to get the images. With that said, mogrify won't work when I have many to process from different source directories to different destination directories? Also I need to check these directories at the source on a perodic bases and process accordingly. So in my script I though I'd issue using convert something like "exec convert 1.tiff FastProcess/1c.tiff &" placing convert in the background (once I got the image). However, if I have 10 images to print, convert is very inefficient when placed as a backgorund process. Aside from processing serially, - which I might, is there a better way?

2) If I compress the image using tiffcp -c lzw, I'm curious as to why the image resolution doesn't change. Doesn't compression affect image quality. Sorry if this may seem like a dumb question.

thanks

Robert

LZW is a lossless compression algorithm. It compacts the space but does not alter the original pixel values.

To speed up your printing process you might want to tweak the tiffcp program that comes with the TIFF delegate library. We're guessing it might be upwards of 10 times faster for large images than ImageMagick.

Thanks for your response. Yes, I had wondered about the lossless compression. So in a case of a non-lossless compressing, which I havent dove into yet, is it fair to expect a drop in resolution?

I didn't think tiffcp was doing any conversion in your second point - though, I am new to this... If so, how does one 'tweak' it to be up to 10 times faster? - which would be very exceptional in a couple of projects I'm getting involved with.

When I say high volume, I mean 4.6 million 28 MB image files. So if there's a way to cut down the processing time at all, I'd really appreciate any insight in tweaking tiffcp to do this. Unfortunately, my imaging skillset is quite novice at this point.

Forget my earlier comment on how IM convert is correcting the photometric interpretation, since I don't see in the man pages for tiffcp, I wonder if/how tiffcp can do this. I also need to process this step in our project.

As far as lossless image compression is concerned, do you know which compression offers the highes compaction without resolution loss?

Again, any help and all help is greatly appreciated.

We can't help you with tweaking tiffcp. This forum is dedicated to discussions about ImageMagick. The tiffcp utility is part of the TIFF delegate library and questions about it is better suited to their mailing list / discussion forum.

That's too bad. By you post, I had thought you had done this...

So is it convert which is doing the photometric interpretation conversion or tiffcp?

You were looking for a fast solution for your problem and tiffcp is probably the fastest but it does require a patch to change the photometric interpretation. ImageMagick is designed to handle a great many image formats so we had to make compromises that sometime make it slower than specialized code that handle a particular image format.

Thanks.. I see a patch for tiffcp from 1994. Do you know of a link to get something applicable to 3.8.2?

Post to the TIFF mailing list or discourse server for questions about tiffcp.