You do not have to resize your full resolution images before uploading them as MyPhotoApp will automatically create resized copies for you at 1024 pixels on the long side and upload them.
But resizing your images before uploading them is recommended because you get:
- Full control over the image quality
- Faster upload speeds
- More Responsive Apps
The ideal size for most uses is 1024 px on the long side. DPI is not important. This size is a good trade off for quality vs performance of the Apps as upload and App responsiveness will be faster and the images are at a quality that most photographers find acceptable.
You can reduce the size further if you are adding a lot of images and speed is the most important factor.
If you want images to be displayed at the best quality, especially on computers and tablets, resize them to 2048 px on the long side. You will also need to adjust the gallery section setting to adjust the "Upload Max Size" field to 2048.
There is a limit of 150 photos per gallery.
It is a good idea to try and limit the number of images in an application to less than 50 in order to have a responsive mobile application. Apps with a lot of images take longer to load and while that may be OK for the person who you give the App to, but when they share it with others, they may not be as keen to wait for the images to appear. So it will hinder the viral nature of Apps and reduce the likelihood of others sharing it with their friends and family.
TIP: If you use MyPhotoapp to send proofs to your clients and regularly include more than 50 Images consider sending them one app with all the images and another with highlights to share with their family and freinds.