On QQ International for Windows all pictures received during a conversation are compressed to optimize data transfer performance. To see the pictures in their original size you need to double click on the picture itself.
The picture will appear in original size in a pop up window as below.
You can also save your pictures and add/edit emoticons into your pictures. To save pictures just hover your cursor over the picture and click the “Save as” icon as below. To add/edit emoticons, just hover over the picture, and click the “Emoticon” icons.