New size limitations on image attachments

[Cynthia Daniel]

The file dimensions will still be 400 wide by 600 pixels high. However, the number of allowed kilobytes will be less: 262,144 kilobytes. This is still a huge amount!

During the upgrade, I found many files that were much larger than necessary. Considering that we have over 6000 attached images and considering that on many of the large files I was able to save 75-95% of the size by simply opening the files and choosing a different compression level, I thought this was worth addressing.

If you check out the attached images you will see that there is virtually no discernible difference in quality, but a very dramatic difference in sizes. The first image has more compression and the second one less.

[Chris Saper]

I can sometimes handle expression, often depression, but I am so sorry to say I really don't get compression.

I see that when I save an image it gives me the slide of min-max, but I really don't know what this means. Does width in pixels x height in pixels have any relation to file size? What do I do from the initial large file that comes out of my camera (which might be .tif, and maybe 2300 x something pixels)?

[Cynthia Daniel]

I copied the following from a web site and I feel it's a good explanation. There's much more information there and worth reading: http://www.shortcourses.com/how/files/files.htm

Regarding minimum and maximum levels of compression, the more you compress (more towards the maximum side of the compression scale), the lower the quality. But, as you can see with the examples I used above, the visual difference is imperceivable on a monitor with the level of compression I chose, but the difference is size is great.

This information about handling images has value way beyond it's use here on the forum. Understanding this applied to image manipulation anywhere.

How Compression Works

During compression, data that is duplicated or which has no value is eliminated or saved in a shorter form, greatly reducing a file

[Michele Rushworth]

Chris, compression has to do with the relationship of a jpeg file's image quality and the amount of computer file space it takes to store it, or bandwidth to transmit it. It doesn't have anything to do with the actual pixel or print dimensions of a file. A tif file from your camera uses no compression at all and gives the best quality, but takes up the largest amount of storage.

When you store a file as a jpeg in Photoshop, and you choose the absolute lowest quality/highest compression setting, the number of megabytes the file takes up will be dramatically less. Unfortunately the appearance of the file can be dramatically worse too. It can look all fuzzy and lumpy (the best words I can think of to describe what over-enthusiastic jpeg compression looks like. Try it and you'll see what I mean.

Somewhere in the middle of the quality/file size continuum usually works best for web images. No noticeable degradation in quality (at least at computer screeen resolution) and a lot less storage space taken up on the server.

[Cynthia Daniel]

Michele,

We were pressing the submit button at the same time.

Chris,

I would recommend saving your original tif file as the source file and then make jpgs from that. Tifs are needed if you ever want to do hard copy printing. Tifs are very large and some people save them on CD to save hard drive space.

The dimension in pixels has something to do with amount of hard drive space an image consumes. But, as you can see in my examples, the dimensions were all 400 x 600, but dramatic differences in hard drive space consumed.

[Steven Sweeney]

We were pressing the submit button at the same time.

Do they ever issue these to guys, or do only girls get them? I'm going to check eBay.