What is the best image format to put on your site

[ClaireH-184886]

Hi at the moment i am working with images to try and speed up my site and i am wondering what is the best format to save images and then put on my site.

I have been playing around with  photoshop where they have the following formats

png-24

gif (but not sure which one i should choose

or jpeg

I would be grateful for your advice and also to know what size i should try and keep the image down to

many thanks

[ChaseFleming]

PNG images are generally large files, take up a lot of disk space on your server, and slow down the load time of your site because they have more data to deliver. I generally stick to JPEG image files and sometimes save in lower quality to lower the file size. GIF would also be fine. The only problem you may run into is with JPEG image files that have transparency. In that case, I generally just use PNG or a GIF, but I typically only use transparent images in headers so it is not often an issue.

[AlanMosley]

The formats do different things.
If you have straight lines in your image like you would in a chart, don’t use jpg use png instead. Jpg can not handle straight lines, it burs them.
don’t use gif unless you need it to be animated
Use png-8 or 24 are fine for most things but jpg is often smaller.
png 8 and 24 both do transparency, but png 8 transparency does not work in ie6

png24 is good for all occasions but is not always the smallest

[AWCthreads]

I go with whatever format provides the cleanest appearance in the smallest file size.

If you shoot the image - shoot the image in the best quality at the lowest file size. I shoot with a professional grade Canon camera in a medium file size which produces a 2mb file. I can render it down from there.

If you have no control over the original file, create a new file in Photoshop at 72 to 100dpi. You won't need to go over 100 dpi on the file as you prepare it. If the image you are working with is poor keep the file at 100dpi while you work with it. If it is a clean and crisp image you can work with it in 72dpi.

Once you have your image ready to save for the web, click "save for web devices". Then, you can choose how you want to save it. For instance, JPEG will allow you to save it at maximum to very high to low. You can watch the file size change as you move from jpeg to gif to png in the lower left corner of the page. We try to keep all of our images at about 10k to 15k. Watch the quality of your image as you render it to different sizes. If your website allows users to enlarge an image for details, you will not want to render the file so small that it compromises the crispness and clarity of the image.

Keep in mind that naming your file is important for SEO purposes. Don't just give your image a generic combination of letters and numbers, but work your keyword into the name of the file. For example, don't load the file to your site as ABC Blue, but rather Carhartt S209 Blue.

[ClaireH-184886]

thanks for this as at the moment image quality is a big problem on my site as well as load speed

[AWCthreads]

Hi Diane. This is timely, we just finished up rendering a bunch of our images to improve page speed.

I'll also throw this in there. Sometimes you won't be able to reduce a file size sufficiently by "save for web devices." When this happens, you can open Bridge in Photoshop and use Photoshop's image processor to render it to a smaller size and then save it for the web.

From Bridge, select the file (or files - you can do it in bulk). Go to tools>photoshop>image processor. From there you can select three ways to save it (jpeg, psd or tiff). If jpeg is acceptable for your situation, select jpeg and choose to render it to low, medium or high.

We were able to render them to 1 or 2 (low) without the image becoming too lossy. Then you can open up the image and "save as web devices" and reduce the file size to a more acceptable size.

Keep an eye on the quality of the image as you go through the steps. I'll trade off some speed for quality appearance.

Be careful when processing files in bulk. You may have ten images and 3 of them won't be able to be rendered down as low as the others and you'll spend time re-doing things.

Good luck!

[ClaireH-184886]

thanks for that, i will try that now. i am getting different results for my site speed www.in2town.co.uk and would be grateful if people could put the site speed here so i can see real results