Resharp Function Sharpness Control 2018-01-02T20:30:23+00:00

Resharp Function Sharpness Control

This image shows why Resharpening most images is required even without photo enlargement. The left side shows the image without Resharpening applied. The right half shows how much more crisp and clear the image is with Resharpening applied. Click the small before and after images below to see the before and after versions with and without Resharpening.

Before and after image resharpening

All digital images can benefit from being sharpened. This is especially true for enlarged images, but enlarged or not, all captured images – digital or analog – suffer from blurring or softening of detail in some way. This is precisely the motivation behind Kneson Software’s addition of the Resharp function in Imagener Professional and Imagener Unlimited. However, our customers have been asking for more information about this function as use of it does require a certain level of skill and knowledge to master.

Blurring occurs when the representation of an object is at a lower contrast or retains less detail than is present in the original. Sharpening compensates for this loss by improving the visibility of the information in the image. It works by applying a matrix of numbers over an array of the pixels in the image with the matrix centered over one pixel at a time. Sharpening can add image data that improve the appearance or impression of sharpness.

This function is formally known as “Unsharp Mask.” We named it “Resharp” to avoid any confusion, but the technique is actually a darkroom technique for improving the sharpness of paper prints that were used before the age of digital pictures.

There are three variables to the function, Amount, Radius, and Threshold. Each variable interacts with the other so it is possible to obtain nearly identical effects with very different settings. Keep the following characteristics in mind:

For example, the images below were enlarged using Imagener Unlimited. The image used was of somewhat low resolution, hence the slight blur that appears in the image to the left. Using the Resharp settings shown at the right, the image below right is made to look much more visually appealing. Edges contrast better, and the overall appearance is improved.

Resharp control box

General Guidelines

Start your resharp operations with the following settings as a guide.

You may discover that the wrong settings can create bright, bare patches. Make sure you remember your enlargement settings as you will need to click the Reset button if this occurs. Keep experimenting. With practice, you will increase the visual clarity and appeal of your enlarged images.

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