有没有办法使用C＃压缩分页的.tiff文件？

Question

At the end of my process, I need to upload several paged .tiff file images to a website. The files need to be very small, 500kb or less when i upload them.

The problem is, even with me resizing them a lot but at the same time being able to read a few lines of text that are in some of them, they are around 1mb each or so.

I first resize all images going into the tiff files but it's not enough. I need a way to change the quality of them to decrease their size as well.

Can C# do this or would I need a third party software to do it?

The files being uploaded MUST be .tiff.

Answer 1

You don't provide much detail about your data, so can only make some guesses as to what you might need to look at.

First, can you loose some resolution? Can you make the images smaller?

Second, can you loose some color depth? Are you saving the files in a color format when bilevel or greyscale images would suffice?

Third, how clean are these images? Are they photos, scanned documents, what? If they are scanned documents of text or drawings, then some pre-processing to remove noise can make a significant difference in size.

Lastly, what compression method are you saving the file with? Only a lossy format is going to give you the highest degree of compression is most circumstances.

Based on your follow-up:

1) If you can make smaller, this of course saves significant storage space. Determine what is the minimum acceptable resolution that they need to be and standardize on that.

2) If you need to persist color, then this step might not be as effective, since you would have to algorithmically decrease the dynamic range of colors used in the image to an acceptable level before compressing. If you are not sure what this means, then you would probably best skip considering this completely unless you can spend time learning more about image processing and/or using a image processing library that will simplify this for you.

3) I don't think you addressed this in your comments. If you want more precise help, you should update your original question and add much more detail about what you are trying to accomplish. Provide some explanations of what/why you need to do in order to help determine what tradeoffs make sense.

4) Yes, JPG is a lossy format, but I think you may be confusing a few different things (or I may not be understanding your intent from your description). If you are first resizing your original images down into a new JPG file (an intermediate image file), then you are building a TIFF file and inserting the resized JPG as a source image into a multi-page TIFF and saving that, then you need to realize that the process of how the files are compressed in the intermediate files do not necessarily have any correlation with the compression format used in the TIFF file. Depending on what you are using to build and create the TIFF file, the compression format used in the TIFF is done separately and you probably need to specify those parameters when you save that file. If this is what you are doing, then the intermediary process of saving the JPG files may be increasing the size a bit.