Have you tried it using image viewer?
Using image viewer we can set the resolution.
Double click the ImageViewer to open its properties. On this form you can select the default image, width, height and if the viewer should show the thumbnail or full image.
Please find below link:
I solved the problem by using and extending a module called image crop.
Allows to create “configs” for image upload, mainly to hold settings such as JPG compression rate.
I extended this by upload-min-width and upload-min-height as well as aspect ratio (offering the user a dialog to crop the image within the defined aspect ratio.