An image rendition is another huge benefit to content authors. In previous versions of SharePoint there were challenges around managing the images for articles or posts and the associated images for the thumbnails of those articles.
SharePoint 2010 just could not resize on the fly which through my own experience was a real disappointment and quite a pain.
Now with SharePoint 2013, image renditions facilitates the uploading of full size images and then the creation of versions of the same image cropped into pre-defined Image Templates and use them in Web Parts or other purposes.
This also allows us to optimize images for mobile devices and can help to improve the user experience of website by optimizing images. Using Image Renditions we can have original (large) images stored in website and then define a number of scaled variants to be used throughout the website.
In most cases while writing any blog posts or adding any announcements item, user want fixed size images. We can achieve this using Image Renditions capabilities.
Before explaining the steps how to use Image Renditions we need to take care of performance as well. To minimize the performance impact caused by dynamically rendering images, the Image Renditions capability depends on the BLOB cache which caches generated renditions. For this mechanism to work properly, we have to enable the BLOB cache for Web Application in web.config.
Note: If BLOB is not enabled then we can not access ‘Image Renditions’ under ‘Look and Feel’ . The SharePoint Site should be either Created from a Publishing Template or has Publishing Feature enabled.
How to Use: We will create one site column of type “Image with formatting and constraints for publishing” in our SharePoint site which allows end-users to choose images from a Site Assets library.
Step 1: Navigate to Site Columns in Site Settings under Web Designer Galleries
Step 3: Newly created Site Column is available under “Custom Column” group.
Step 4: Add this column into Announcements list (I am going to use Announcements list for this example). Click on “Add from existing site columns”
Step 5: Select the new “ImageRenditions” Site Column that we created above and Click on OK.
Step 6: Create new list item to view ImageRenditions Image Site Column. Select any “Template” from Image Renditions drop down after selecting specific image from Site Assets (Or from other resource) and click on OK.
Note: Uploaded images (Hero-1.jpg) actual size is 1182X1000.
Step 7: Now you can notice the Image is uploaded with the size that was Chosen in Image Rendition Display Template (100 x 100 in my case).
Step 8: Click on Save and item looks like below.