No sure if you know about this, you can actually copy card images in game if you're using iOS device. This way is easier as you don't have to crop the screenshots of card images and the quality of the picture is better. So for e.g. if you wanna get a card picture in game, simply:
- Go to the page displaying the card details.
- Tap on a word or area of the screen and hold your finger down.
- When the magnifying glass pops up, you can remove your finger. When you do this, the copy and paste pop up menu will appear and you'll see a the word you tapped on highlighted.
- Select the card image and tap copy.
- Now go to email and create a new email message.
- Paste the picture into the email content by tap on a word or area of the screen and repeat the process. When the copy and paste pop up menu appears, choose paste and the card image will be pasted onto the email.
- Just send the email to yourself and you save it onto a computer and upload the images
Hope this helps. =)