1. Image resolution
All images that are larger than 1920 pixels, in width or height, before upload will be resized to 1920 pixels during upload. To avoid quality loss, we recommend that you upload images that are 1920 pixels or smaller. Note that images that are smaller than 1920 pixels, will not be resized.
What about dpi?
Dpi (dots per inch) only matters when it comes to printing or scanning. Monitors don't have dots but pixels, so dpi value has no effect on the quality of an image viewed on a screen or uploaded online.
2. Image size
To upload an image in Portfoliobox, the file size cannot exceed 12Mb. The file size of an image is measured in kilobytes (K), megabytes (MB), or gigabytes (GB). The file size is affected by the pixel dimensions of the image and its format. Because of the varying compression methods used by GIF, JPEG and PNG formats, file sizes can vary considerably for the same pixel dimensions.
3. Image color profile
Before uploading your images to your Portfoliobox site, make sure their color profile is sRGB. If you are using Photoshop go to File > Save for Web. This will make sure that the images will be optimized for web browsers.
4. Image quality
The higher quality your images have, the heavier the files would be. When you have lots of big and heavy image files on your website, it will affect your page speed. You can speed up the loading of your website by slightly reducing your image quality. In Portfoliobox, you can adjust the image quality by clicking on the Cogwheel Icon > Settings > General > Website > Image Quality. The image quality scale is from -1 to 1. -1 is the lowest and 1 is the highest. You can try out different quality level to find the best option for your website.