All images uploaded to JOYclub are automatically recompressed shortly after upload. Depending on the display resolution of the end device, other variants of the image, with more or less resolution, are therefore displayed.
"The one optimal resolution" that an image must have before uploading to fit perfectly on all screen types does not exist. There is only the resolution that your phone, tablet, laptop or high-resolution monitor can display optimally.
JOYclub takes care of all conversion cuts fully automatically. So you can use all image formats and resolutions with a clear conscience and be sure that they will be displayed optimally on all devices.