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Resize Your Images

Should you resize your pictures? If you have a full resolution photo or graphic then the answer is probably yes. Your images shouldn’t be wider than your page width (900px max for a one column, 600 px for two column, 400 px for three column). Aim for a file size of around 300KB or less per image.

Because images shouldn’t be larger 900px wide, you might be tempted to scale down an oversized image in Omni or WordPress. Don’t do that – resize your pictures before you upload them. Just because you resize your image on the page doesn’t mean it’s a smaller file size. For example, if you upload a 5MB picture with dimensions 2000×2000 px, changing the dimensions to 100x100px will only change the display of that 5MB image. Every site visitor will have to download that 5MB image which has been only been scaled down in the browser. This makes it difficult and frustrating for your website visitors when they have slow internet connections. In the case noted here, it would be better to scale down your picture to 100x100px in a photo editor like Pixlr and upload it to your website. The file size will be much smaller and your page will load faster without a large image file slowing it down.

If you come across a slow or unresponsive web page, it’s often because someone uploaded a huge file. We have seen users upload image files as large as 34MB! Don’t do that! Keep your file size low and in kilobytes (KB) not megabytes.

How to Resize Your Photos in Pixlr

Go to the Pixlr editor site http://apps.pixlr.com/editor/

Click Open Image from Computer

We are going to upload a picture we found on the Vanderbilt Flickr stream.

Kirkland Hall with downtown Nashville. (Daniel Dubois / Vanderbilt University)

Image Details
File Size: 2 MB
Dimensions: 1640 x 1429

Resize your Image

Click on Image > Image size…

Type in the width and height dimensions for your image. Make sure Constrain Proportions is selected so the image scales proportionately. Click OK

General Image Sizing Guidelines

One Column Page: Width: 900px
Two Column Page: Width: 600px
Three Column Page: Width: 400px

The width is suggested instead of the height because you don’t want your images to be wider than the width of your total page width. Most Vanderbilt websites are 950 pixels wide total, but the content area is smaller for two and three column pages. These image guidelines will help you stay within the width of your page layout to account for page margins and padding. You also wouldn’t want a really tall image either that pushes down the rest of your content.

Slideshow Image Sizes

You’ll need to use different image sizes for your slideshow images. Notice that both width and height are specified for the slideshow images.

Slideshow Setting Image Sizes
Wide: 950 x 300
Yes: 650 x 300
Mini: 460 x 300

File Size

Keeping your file sizes low makes your pages download friendly to your site visitors with slow internet connections. Images displayed on your pages are automatically downloaded by site visitors. Large images (1MB and higher) can take a long time to load and your site visitors might leave before they even see your page. Large image files also create a lot of unnecessary strain on server resources.

Save your Image

Go to File > Save to save your image

Pick either PNG or JPEG from the format dropdown. These are the only two image formats that will work on your website.

PNG
PNG will save the file full resolution which will sometimes result in a larger file size.

JPEG
If you select JPEG format you can adjust the quality setting to reduce the file size. Don’t lower the image quality too much or the picture will become pixilated and distorted.

Image Details
Compressions: 30% (Quality: 70 in Pixlr)
File size: 69KB
Dimensions: 450 x 302


70% compression gave us a 69KB image with dimensions of 450×302

A Note about Compression

Lowering the quality a bit can can slim down the file size, but don’t overdo it. Let’s see what happens when we crank the compression all the way down to zero


Will give you a result like this.

Image details
Compression: 100% (Quality 0 in Pixlr)
Size: 6KB
Dimensions: 450 x 302

It’s only 6KB but image quality has been deteriorated so much that it can’t be used
(unless you are making pixel art).

Summary:

  • Resizing your images in Omni or WordPress changes the width and height, but not the file size
  • Resize your images in a photo editor like Pixlr before uploading them to Omni or WordPress