If I can shrink a 2 gig video down to 17 megs, and still have it looking good, there's gotta be something for images!
September 17, 2008 4:19 PM   Subscribe

Software to reduce image size for websites?

I've used Photoshop in the past to shrink image size for websites, but is there anything better that I could be using?
posted by Sufi to Computers & Internet (15 answers total) 2 users marked this as a favorite
Better how?
posted by RustyBrooks at 4:27 PM on September 17, 2008

The reason you can shrink video a lot is that you compress it heavily.

JPEG image files, however - which I'm going to assume you're talking about - are already super-duper-compressed. There are little speedy apps that will be faster than Photoshop to do the same save-as-jpeg/resize operation, but you're really not going to do any better in any other respect.
posted by Tomorrowful at 4:32 PM on September 17, 2008

I don't think you'd gain enough to be worth the trouble. If your web site's slow due to image size, you're doing something wrong, and you'd be better off with a valid HTML/CSS layout if you're not already using one.

I use Photoshop's Save for Web... and do either JPEG Medium (for photos) or GIF 32 No Dither (for almost everything else) for almost everything and the image sizes are fine. They could be smaller, but not smaller enough to make a difference.
posted by kirkaracha at 4:33 PM on September 17, 2008

2 GB to 17 MB is about a factor of 120. The comparison you're looking for is not between JPEG and something smaller, but between uncompressed images and JPEGs. Taking RAW images as an example, which is close to uncompressed but not really, let's say you had an 8 MB RAW image. Compressed into a JPEG, and on the best quality setting at that, you can get down to about 800KB, which is a factor of about 10. You can easily squeeze that further by reducing the canvas size and lowering the quality settings on your compressor, or using techniques more appropriate for the particular image, like a restricted palette, or a different compressed format.

Short answer: You already can do with images what you can do with video. That's what JPEG and other compressed formats are.
posted by odinsdream at 4:38 PM on September 17, 2008

picaview is an easy 2 click process, but the photoshop results are better controlled. there are also a lot of websites that'll do it online if you don't want to install anything.
posted by nadawi at 4:41 PM on September 17, 2008

what do you use to compress huge video files that much?
posted by alitorbati at 4:46 PM on September 17, 2008

Perhaps you could use Photoshop's batch tool? So you don't have to repeat your settings with every image.
posted by pantsrobot at 4:48 PM on September 17, 2008

I think he's concerned with image size, not file size.
posted by davebush at 4:56 PM on September 17, 2008

Sorry - I hadn't read the post title.
posted by davebush at 4:58 PM on September 17, 2008

It's a bit of a nuclear solution to a simple problem, but if you're already comfortable with Photoshop, stick with it. It's very powerful/flexible.

GraphicConverter (Mac only) is smaller and nimbler, and it can often make smaller-er files than Photoshop, though it's quite a bit harder to control quality.
posted by rokusan at 5:14 PM on September 17, 2008

Photoshop wussies...
convert -resize 600 DSC00008.JPG tb_DSC00008.JPG
Image Magick.
posted by zengargoyle at 5:43 PM on September 17, 2008 [1 favorite]

ImageWell is a total lifesaver! I use it all the time. It does just what you want and is very fast and light. It's also a free download.
posted by toomuchkatherine at 6:07 PM on September 17, 2008

I like the way the "save as jpeg" feature works in GIMP, because you can fiddle with all the JPEG parameters and get a live preview of how the result is going to render before committing it to disk. You also get to see what the file size will be. Makes it very easy to trade file size off against image quality on a case-by-case basis.
posted by flabdablet at 8:01 PM on September 17, 2008

To answer some questions:

The site's fine, no loading issues or anything.. I was just so surprised at the results of my video compression that I wanted to see about getting my images smaller than they already were (largest is about 30kb).

I'm using sorenson squeeze for my videos.
posted by Sufi at 11:55 PM on September 17, 2008

The video compression you are using benefits from a lot of things that single frame compression cant - most notable motion-vectors and interframe compression (MPEG-2, MPEG-4 and others).

While these compression methods usually can't do much better than JPEG on a single frame (in fact often use JPEG or similar for frame compression) they can then simply discard information that doesn't change much between frames, and only save details of changes for each frame, not the frames themselves. It is Three Dimensional compression really (adding temporal compression to the existing 2D image compression).

HDV for example, is MPEG-2 based and spread it's compression over 15-frames at a time. It also uses horizontal resampling (making a smaller compressed frame, 1440x1080 instead of 1920x1080) and then utilises colour sampling patterns to reduce the data even further (only sampling the colour channels at half the resolution of the luma channel). In doing so the datarate for 'HD' video goes from 1330 Mb/s to 25Mb/s - and then you might compress the resulting HD video from that into MPEG-4 H.264 which uses even more agressive versions of the same techniques (as well as things like frame-reordering) to get a datarate of 6Mb/s

This isn't possible with images because there isn't as much data there in the first place. By starting with a massive amount of data both in image detail and through time, video compression has much more potential for compression that static image compression. Also the motion of video disguises a lot of compression defects that would be unplesant if they were applied to a single still image.

That said, JPEG-2000 offers better compression ratios on still images, but isn't really widely supported enough for widespread web-usage.
posted by sycophant at 2:11 PM on September 18, 2008

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