This article demonstrates Healing Brush and related Photoshop tools in action with the help of examples. See Retouch and repair photos if you're looking for basic information on using these tools.
The Healing Brush, Spot Healing Brush, and Patch tool in Photoshop have a Diffusion slider which controls how quickly the pasted region adapts to the surrounding image.
As a general guideline, low slider values are good for images with grain or fine details whereas high values are good for smooth images.
The new healing algorithm is better in diffusing the color and spreading them over an area. However, you need to be very clear about the area being sampled or filled. For soft selection, Photoshop thresholds the soft selection at 128 to display an 8-bit mask. As a result, the screen feedback in patch tool can misrepresent what user is actually sampling or trying to heal. This can manifest itself in bright or dark color contamination at the boundary of the filled area, which will be spread over the filled area. The new algorithm is enhanced to deal with very soft brushes. To limit the contamination, you may want to try different diffusion slider values and be careful with the sampling region. The patch tool can be prone to this sort of error as illustrated in the next example.
The next six examples will compare the effect of various slider values on the healing result. The focus will be on the content with noise, high texture, and details.