Easy prevention of unintended lines after crop in Photoshop cs6?

Question

After cropping and saving for web as jpeg (maximum, optimized, convert to sRGB selected) there are unintended 1px gray lines around the border of my images that have a white background. I've read that I can flatten to remove these, but do I flatten first then crop, or crop and then flatten? I imagine it's the former. Are there other ways to prevent these lines?

Answer 1

You can eliminate those gray lines by eliminating the white background before you save for web. Most likely the lines are the anti-aliased edges on the between your image and the white background. If there's no white then the jpeg compression step won't create the gray line difference between the two parts. If you're doing a lot of images like this, you can setup an automated action to save time.