• "Blur, Sharpen, and Smudge Tool" are used for retouching the images.
• These tools are also called as Focus Tools.
• The "Blur Tool" is used to soften or harden the uneven portions of an image.
• The "Sharpen tool" is used to increase the contrast, clarity of an image.
• The "Smudge tool" is used, to blend the portion of an image together.
• These focus tools gives an effect of touching wet paint with a finger.
• Use these tools by simply selecting the tool from the toolbars and click and drag over the image and see the difference.
• Before that choose the brush size of your choice from the focus tools "Options Bar".

Video Tutorial: