In order to add a high resolution picture to a smaller, lower resolution picture in Guidelines, you must link the smaller picture in Guidelines to the desired high resolution picture in the asset bank.
1. Start by uploading the image to the asset bank. See the article How do I upload assets to Bynder? if you're unsure how to upload an asset.
2. Once the image has been uploaded to the asset bank, click on the image to see the single asset view. Here, copy the media id at the end of the URL. (It looks something like this: 1EC3E2CB-0363-44ED-B90FDA5F49687EB4).
3. Go to the desired Guidelines page and add the image as you normally would. See steps 1-2 in Am I able to place pictures side by side in Guidelines? if you're unsure how to add an image to Guidelines.
4. Once the image is in the Guidelines page, select the image and add a link. For the link type option, pick 'Link to asset detail'. For the asset ID, copy and paste the media ID from earlier.
Now when you click on the image, you will see the same image in the asset bank as a larger, downloadable version.