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I need to send hundreds of pictures via email. The size is reaching 100s of MBs .. which is certainly burden on network.

WinRar, 7-Zip aren't helping ..

Would you like to suggest any software which can carry out compression so that I can reduce the size and send it via email, and decompress it at the other end ..

opensource or freeware are more preferred .. paid-versions are appreciated too

Edit: I am seeking an alternative software for winrar and 7-zip which is more efficient in compressing .. but still not losing any data ..

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@infant-programmer, I think you really need to explain what format and size the average image is already, because if they are already jpg compressed and the resolution is low, you're not going to gain enough to be noticeable. Also, what are the pictures for. Just to send to friends and family, or for professional graphics services, etc? –  deltaray Feb 21 '11 at 15:30
    
You’re unlikely to find an archiver that can significantly compress JPGs since they are already compressed. You’ll get good archive compression for BMPs and other raw graphics formats, but for anything that’s already using a compression algorithm, you’ll get little if anything from simple lossless compression (you could even end up with a larger archive than the files alone!) If you want to significantly shrink the file sizes, you’ll need to re-encode them either in a different graphics format or by using a lower quality level; either way it’s likely to be lossy. –  Synetech Feb 21 '11 at 17:59

5 Answers 5

up vote 2 down vote accepted

The other thing to consider is reducing the dimensions of the images.

What are the images going to be used for?

If they are just going to be displayed on a screen then an 800 x 600 pixel image would probably be adequate.

Something like ImageMagick (or Paint.NET) will do this for you.

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can I set the image dimension of all the images at once ? :) –  InfantPro'Aravind' Feb 21 '11 at 15:09
    
@infant programmer - yes, though I'd have to do some investigation of the tools to see whether a) batch processing was possible and b) what the exact syntax was. –  ChrisF Feb 21 '11 at 15:12

ImageMagick can do just about anything to pictures, compress, resize, rotate, etc.

However, most JPG or PNG files are already compressed. if you sending raw or tiff images, you can convert them to a compressed image, but you will lose some picture quality.

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Compressing JPG files further will lose quality too. –  ChrisF Feb 21 '11 at 14:30

I simply wouldn't use e-mail. I would suggest creating an encrypted file. For example with truecrypt (Works with win, linux, and mac os). Then i'd put all the pictures in the file and upload that at an freehoster. Afterwards i'd send the password and the link via e-mail.

This is the best method to decrease the e-mail size.

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thanks for the valuable suggestion but .. I would like to know about efficient compression and decompression .. gaining loss-less data :) –  InfantPro'Aravind' Feb 21 '11 at 15:12
    
@infant programmer If you are looking for lossless compression I'd suggest you pack the images. But if you have already compressed image formats like .jpg there won't be much more to pack. If you have an already compressed file you can't compress it more. Packing is not cumulative. If it would be you would be able to compress everything to few bytes. That is why .jpg files don't shrink when packed. –  Darokthar Feb 21 '11 at 15:39
    
Take a look here for an introduction: en.wikipedia.org/wiki/Lossless_data_compression#Limitations You could try tar and gzip. But if the images are compressed you will not win much space. –  Darokthar Feb 21 '11 at 15:45

You won't find anything better than 7-Zip/WinRaR/WinZip for general purpose compression, and it won't help much (about 1%) on jpegs. You also won't find much better than jpeg for photo type images or png for logos/cartoony graphics. Many people have worked on compression algorithms and they are only going to make small improvements from now on, in the general case, rather than any huge breakthroughs. Even if you came across some advanced technique like fractal compression, the receipients wouldn't be able to decompress it.

You need to decide what picture quality and size is important. If you reduce the images to jpeg 20% quality and 800x600 size, it will make an enormous difference compared to jpeg 100% and 12 megapixel say. If you really need the best image quality and full size, then post a DVD to the receipient, use an upload site or otherwise share a folder.

There is also the question of whether the receipients need the full size image immediately. Maybe you could send thumbnails which link to larger images on a web site? That way they only get what they want.

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Yup, JPG is already a compression algorithm, so using another one on top won’t give even more compression, and could even increase the file size. –  Synetech Feb 21 '11 at 18:01

There is software available now that does compress JPEGs losslessly to a significant extent (20 to 25%). Packjpg is free - there is also a GUI interface available for it.

Stuffit is a commercial program that compresses JPEGs and can achieve about 25% compression.

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