Question about the file size of an image

MikeAldrich · May 13, 2014

So, Im having a bit of a brain fart this morning trying to resize some images for web use. Our website guy needs images all set to a height of 800 pixels with a file size around 100K. So, Ive resized the images to a height of 800 pixels and set dpi to 72. The pixel dimensions are somewhere in the neighborhood of 1.4M. The file size is 563K though. I found an older edit of the same image, this one had the height set to 900 pixels at 72 dpi. The pixel dimensions on this image is 3.18M, but the file size is 151K. Its the same exact image, set roughly to the same size but with two different file sizes. How do I get the file size down around the 100K mark?

480sparky · May 13, 2014

DPI has nothing to do with file size. It only applies to printing.

800 pixels is a good web size. Why he's demanding 100k is a mystery.

Braineack · May 13, 2014

image compression.

pixel dimensions is only a part of the final image size.

I could save a 500x500 image out at 3MB or 30KB.

MikeAldrich · May 13, 2014

Okay, I figured out the compression thing. But I'm still not sure what would be an ideal file size for putting something on a website. My images are currently in the file size range of 500-1600K depending on the image. Will these still load quickly or should the file be compressed to something lower?

SCraig · May 13, 2014

MikeAldrich said:
Okay, I figured out the compression thing. But I'm still not sure what would be an ideal file size for putting something on a website. My images are currently in the file size range of 500-1600K depending on the image. Will these still load quickly or should the file be compressed to something lower?

If there are a bunch on the page then, no, they won't load fast. While the days of dial-up internet are pretty much gone there are still a lot of people on ISDN, wireless, and other non-broadband means of internet access.

All of the images on my web site are 800 x 533 and are in the neighborhood of 150kb each. They all have an accompanying thumbnail that is 150 x 100 pixels and in the neighborhood of 20kb each. The larger files are only opened when one of the thumbnails is clicked. Even with the small thumbnails some of my pages seem to take forever to load because there are so many of them.

KmH · May 13, 2014

Pixels can't be set to a dpi, they can only be set to a ppi.

As it is ppi is print resolution and ppi has no effect on image size when displayed electronically.

The file size of JPEGs is controlled by the Quality (compression) setting.
The ideal image file size as it relates to load speed is going to depend on factors you can't control - the network tier your web site provider is at, the configuration of that web site providers server farm, the end user's Internet access speed and general condition of their computer and browser as far as temp internet files that relate to, Browsing History, Download History, Cookies and other site and plug-in data, Cached images and files, Passwords, Autofill form data, Hosted app data, etc.

If your web site is Adobe Flash Player based for image display other issues apply.