Open a graphic-editing program such as Adobe Photoshop, GIMP or Corel PaintShop Pro. These programs provide the best tools to fix problem edges on photos, cartoons, hand drawn illustrations and other artwork.
Use a lasso tool to select around the illustration's perimeter. For example, in Photoshop, click the lasso tool and drag the dotted line to select only around choppy edges.
Select from "Selection" options to smooth or contract the selection. You enter a value to smooth or contract measured in pixels. Enter a "1" or "2" for minor smoothing. This moves the dotted selection inward and creates a seamless line around your illustration. Press "CTRL" and "X" to cut the selection. Open a new document and press "CTRL" and "V" to paste the illustration with smooth edges.
Click on a warp or liquify tool. Find this tool in the filters category. With this tool, you drag your mouse pointer along the edges, moving the jagged edges in and out until you create a seamless edge. Use the zoom feature to get up close with an edge to see all the jagged points. The image moves with your mouse as you drag, so smooth along edges carefully.
Click on the smudge or push tool from the toolbox. In most cases, the smudge tool looks like a hand with a pointed finger. Other editing programs place this tool in the "Image" menu. The smudge tool uses a brush to move and smooth out the image. You also set the strength of the smudge tool. Set the strength to 50 to smudge and smooth an edge without distorting the image too much.
Right-click your illustration's layer in the layer palette and select a duplicate option. A new layer from your base adds to your document. Right-click the top image in the layer palette and select blending options. Set the mode to "Overlay" with a strength of 50. Click "OK" to set, then click on the filter menu. Select the blur option and choose "Gaussian Blur." Set the blur to 5 or 10, depending on your illustration's size. The gaussian blur tool blurs around edges and gives a glow look.