Method of sharpening image using luminance channel

1. A method for sharpening an image, the method including the steps of:

(a) receiving a data set including at least one colour plane indicative of the image; and

(b) extracting an initial luminance channel from the data set, the initial luminance channel being in a colour space different to that of the at least one colour plane; the method being characterized by the further steps of:

(c) sharpening the initial luminance channel to form a revised luminance channel; and

(d) adding the revised luminance channel to at least one of the colour planes of the data set.

2. A method according to claim 1 wherein step (b) includes the step of processing the at least one colour plane to derive the initial luminance channel.

3. A method according to claim 2 wherein the colour planes include a red plane, a green plane and a blue plane and the method includes the step of deriving the initial luminance channel from the colour planes.

4. A method according to claim 1 wherein the data set includes the initial luminance channel and step (b) includes the step of accessing the initial luminance channel.

5. A method according to claim 1 wherein the sharpening step includes high-pass filtering the initial luminance channel to provide a filtered luminance channel.

6. A method according claim 5 wherein the high-pass filtering utilizes a 3×3 convolution kernel.

7. A method according claim 5 wherein the high-pass filtering utilises a 5×5 convolution kernel.

8. A method according claim 5 wherein the high-pass filtering utilises a 7×7 convolution kernel.