Image sharpening and histogram equalization

Image sharpening and histogram equalization Although the effect is enhanced contrast, are image enhancement, but there are some differences.

Image Sharpening

Image sharpening is the edge of the highlighted image (High frequency section), enhance the contrast of the boundary pixels, so that the edge of the black pixels darker, white and white

so a simple sharpening is original image + Edge image * Coefficient

all the coefficients of the sharpened template are added equal to 1

For example, you can use templates

Or

It can be seen simply as the edge Graph + Original of the Laplace operator in the 8 domain, since the center factor plus 1 indicates the pixel value of the original image. so the template is equal to the original image + Edge image *

Histogram equalization

As explained in my blog http://blog.csdn.net/qianqing13579/article/details/41956903, this is not repeated here, the main purpose is to enhance the overall image of the contrast effect

So the main difference between the two is: equalization is to enhance the contrast of the image, and sharpening is to enhance the edge of the contrast effect, highlighting the boundary

Let's do an experiment with PS.

Original

Sharpening template using a variant of the Laplace template for 8 fields

Get sharpening Diagram

Then use PS to do a histogram equalization

There is a picture of the truth, and through these two graphs, the difference between sharpening and equalization is very clear.

Image sharpening and histogram equalization