Image processing method for boundary resolution enhancement
An image processing method for boundary resolution enhancement is disclosed. Firstly, an image is transferred into an image layer. Noise of the image layer is removed by a bilateral filter and crisp edges are retained at the same time. Moreover, the image layer is interpolated by an interpolation filter for resolution enhancement. The image processing method of the present invention can lower the image blur degree substantially, enhance the image resolution and be widely implemented in all sorts of image/video processing hardware devices.
1. An image processing method for boundary resolution enhancement, comprising steps of:
transferring an image into an image layer;
removing noise of said image layer by using a bilateral filter to generate a resolution image layer; and
performing a gradient analysis of said resolution image layer by using a sharpness filter to remove at least one unbalance boundary of said resolution image layer and then to generate a sharpened image layer, and interpolating said sharpened image layer by using an interpolation filter to generate a high resolution image layer.
2. The image processing method for boundary resolution enhancement according to claim 1 , further comprising a step of:
transferring a format of said high resolution image layer into an original format of said image.
3. The image processing method for boundary resolution enhancement according to claim 1 , wherein said image layer transferred from said image comprises an RGB format, an YUV format or a CIE-Lab format.
4. The image processing method for boundary resolution enhancement according to claim 1 , wherein said bilateral filter is an Inverted Intensity Gaussian Bilateral Filter (IIG bilateral filter).
5. The image processing method for boundary resolution enhancement according to claim 4 , wherein said Inverted Intensity Gaussian Bilateral Filter removes said noise of. said image layer under a condition of:
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whereas B(.) is a pixel's intensity value, c is a pixel, a is a neighbor pixel of c, I(.) is a color space returning a pixel intensity, P(.) is a pixel position, D(.) is a distance function, C is a constant; and said equation (1) represents that a spatial domain and an intensity domain of a pixel are simultaneously processed with a Gaussian blurred algorithm in said image layer, such that noise of small illsuminance variation is smoothly removed and edges of large illsuminance variation are retained.
6. The image processing method for boundary resolution enhancement according to claim 1 , wherein in the step of sharpening said resolution layer by said sharpness filter, pixels of said resolution layer are divided by Data Dependent Triangulation and each of said pixels has a diagonal line.
7. The image processing method for boundary resolution enhancement according to claim 6 , wherein said resolution image layer is divided into a plurality of horizontal blocks; a horizontal pixel field is formed along said diagonal lines in each said horizontal blocks; and said horizontal pixel field is generated by said sharpness filter.
8. The image processing method for boundary resolution enhancement according to claim 7 , wherein two of said diagonal lines which are adjacent have an intersecting point and said horizontal pixel field based on two said diagonal lines is in a triangular shape.
9. The image processing method for boundary resolution enhancement according to claim 7 , wherein two of said diagonal lines which are adjacent are parallel and said horizontal pixel field based on two said adjacent diagonal lines is in a quadrilateral shape.
10. The image processing method for boundary resolution enhancement according to claim 6 , wherein said resolution image layer is divided into a plurality of vertical blocks; a vertical pixel field is formed along said diagonal lines in each of said vertical blocks; and said vertical pixel field is generated by said sharpness filter.
11. The image processing method for boundary resolution enhancement according to claim 10 , wherein two of said diagonal lines which are adjacent have an intersecting point and said vertical pixel field based one said two adjacent diagonal lines is in a triangular shape.
12. The image processing method for boundary resolution enhancement according to claim 10 , wherein two of said diagonal lines which are adjacent are parallel and said vertical pixel field based on said two adjacent diagonal lines is in a quadrilateral shape.
13. The image processing method for boundary resolution enhancement according to claim 1 , wherein said sharpness filter is a high pass sharpness filter.
14. The image processing method for boundary resolution enhancement according to claim 7 , wherein said interpolation filter computes center pixels in said horizontal pixel fields and opponent pixels relative to said center pixels to generate interpolated pixels for interpolating said sharpened image layer.
15. The image processing method for boundary resolution enhancement according to claim 10 , wherein said interpolation computes center pixels in said vertical pixel fields and opponent pixels relative to said center pixels to generate interpolated pixels for interpolating said sharpened image layer.
16. The image processing method for boundary resolution enhancement according to claim 1 , wherein in the step of using said bilateral filter to remove noise of said image layer, said bilateral filter computes blurring effect; and predicts computing complexity in light of said blurring effect; when a hardware is overloaded with said computing complexity, said noise of said image layer is removed by a Gaussian blur filter.