Photo compression

I am working on a website with logs of my various lighthouse trips, accompanied by photographs. Having split each trip into individual days, I have about 8-10 digital photos per page, which is a bunch of big files.

To get this number down, I'd like to compress them. However, I cannot figure out a good amount to compress. I tend to use Photoshop 6 for compressing my images. I use the save to web feature, however, the images are either too big (at least I think), or they become to monotonous in color.

I know that some of you have large photos that you must compress to post here. However, these do not seem to lose detail. How much do you suggest compressing so that I can achieve the same good balance?

Any help is GREATLY appreciated!

Greg --

Saving your images as JPEG ( Joint Photographic Experts Group ) will compress them as compared to TIFF images or BMP (Bitmap).

There are three things that determine the file size of JPEG images (and thus the time it takes to download or display them): the physical size of the image, the resolution, and the 'quality' level at which it is saved.

Keep in mind that some people will still view the Internet on a monitor that displays 640 x 480 pixels. Anything wider than 640 pixels and these people will not be able to view your image in full with a browser. I tend to design with the viewer who has a display resolution no smaller than 800x600.

My suggestions:

1. Set the image size of each picture to a maximum of 500 pixels in width or height (whichever is longer)

2. Set the resolution at 72 dpi. Anything higher and you are simply wasting bandwidth.

3. Set the quality at about 6-8. The scale can be from 1 to 12.

You can run a test by setting up one image saved at 72 dpi that is 500 pixels wide and then saving it at various quality levels. Put them all on the same page and mix them up. See if you can tell which is the higher quality image.

Another technique would be to make thumbnails of your images that are about 150 pixels in width and require the individual to click on the thumbnail to view the larger image. This saves those on dial-up connections a lot of waiting time and they will click on only the images they want to see in larger size.

You can view thumbnails at:

www.HarbourLights.com/catalog/2004/index.htm for example.

Here are three JPG images. All three are 72 dpi with an image width of 500 pixels.

One was saved at Quality #2, another at #8 and another at #12.

Which is which (without peeking)







One of these has a file size of 65K, another is 103K and the highest quality one is 313K, almost 5 times the size of the lowest quality one and 3 times the size of the middle quality one.

John,

Maybe it's because it's after midnight. Maybe it's because I broke a tooth today and it HURTS like crazy. Maybe it's because my eyes aren't quite what they used to be. Or maybe it's because I'm just a tad ignorant.

But to be totally honest with you, I cannot tell the difference. Sorry.

Bob

That's pretty much the point, Bob... On the Internet for most images, you won't be able to tell the difference on a monitor.

Without peeking the first one is the lowest and the middle one is the highest...

It is a little difficult to compare because you have to scroll between them.. The main giveaway is in the detail in the chair..

Greg try fewer pictures per page or a smaller picture that links to a bigger image of that same picture on a page by itself..

I generally don't like what I get under a 6 setting as some of the detail does start to break down..

I got what Paul got, by concentrating on the detail of the brick. But if you only saw the first one you'd think it was a pretty good picture.

I spotted the bricks and the legs on the bench as being the give away regarding which file was the largest.

Bob

All those who guessed correctly win a Sea Girt LLOM. Sorry Greg......

Thanks for the tips, everyone! I have figured out how to get it to be between 3-10K, without losing quality. I appreciate all the help!

Look out for my website launch soon! I'll post a link as soon as it's ready...I just have to make the page for my CT/RI/MA Tour.