I don't think it will be the image size that is the issue here.
Open the image file up in and editor (Photoshop or similar) to see if there are any wrong pixels at the edge of the image that is causing the line.
If there are you will need to crop them off so you will get a clean join.
If that is not it and the join changes as you zoom it may just be a display problem.
Try printing (to a PDF should be fine) and see what that looks like.
Barry.
One of the forum moderators.
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