Healing

BranchesThis technique involves eliminating small blemishes or unwanted parts of an image by painting over them with adjacent background colour and texture. Doing this well can be a time consuming task, but the results can really improve an image. Some programs use the clone tool to perform this task, other programs provide a dedicated tool, usually called a healing tool.

The image shown on the right looks fine in its small, web-sized version. However, if you were to inspect the full sized image closely, as you would do if you were preparing it for a high quality print, then you would notice a number of small blemishes in the blue of the sky that would be visible.

ContrailThe image on the left shows a close up of the left edge of the picture. Notice the faint white contrails in the sky where a jet has recently passed over head. This needs to be removed from the image.

In the GIMP the healing tool can be found in the toolbox, on the Tools>Paint Tools menu, or by pressing H on the keyboard. In PhotoShop you can find the healing brush on the toolbox with the sticking plaster icon.

To use the tool you must first select an area to use as the replacement colour/texture. In this case I used a clear blue portion of sky just below the contrain. In PhotoShop you point at the region and hold down the ALT key and click. Then you can use the tool just like a regular brush tool except the brush paints with the colour/texture from the selected region. PhotoShop shows you exactly where your healing texture is coming from by displaying a small grey cross hair on the image as you work. You will notice that this cross hair tracks your movements.

The source region dynamically tracks the healing brush as you work. This is so that the healing is a close match to the adjacent colour and texture. Even so, sometimes it is necessary to reselect the source region to ensure that you get a good match across the entire healing. You can see the result of healing by rolling the mouse over the image. After carefully painting with the healing brush, there is no hint of any white contrail, and the sky is a uniform blue.

BustReplacing some jet trails with a fairly uniform blue is quite easy and could also have been done simply with the airbrush tool. However, the healing tool is also able to work convincingly with natural textures as well. Consider the picture shown on the left. In this case I did not even notice the loop of string until after I had uploaded the image to my computer.

StringTrying to remove this with an airbrush would result in a very flat and unnatural result. However, the healing brush allows us to get very good finished image.

The close up on the left shows the region of the image in some detail. Hover the mouse over the image to see the result of careful application of the healing brush to the area.

Using a fairly small brush size (10 pxiels) and being careful, at each stage of the process, to ensure that I was selecting the healing texture from an appropriate region of the image, I was able to remove the string. An important aspect to successful use of this technique is patience. Take your time and work carefully!

You can find a good article with much more detail about using the healing tools in photoshop here:

Digital Photography School - Using the Healing Tools in Photoshop

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