Method, apparatus and a unit for image conversion

1. An image conversion unit for converting a first image with a first resolution into a second image with a second resolution, the second resolution being higher than the first resolution, the image conversion unit comprising:

an image converter for converting a first image with a first resolution into an intermediate image with a second resolution, the second resolution being higher than the first resolution;

a noise adder for adding noise to the intermediate image, wherein the said noise comprises spectral components that are in a part of a frequency spectrum that is above the Nyquist frequency of the first image; and

a spatial enhancement filter for enhancing structures of said intermediate image which is based on the first image and which has the second resolution,

wherein a combination of said noise adder and said spatial enhancement filter forms said second image.

2. The image conversion unit as claimed in claim 1 , further comprising a noise generator.

3. The image conversion unit as claimed in claim 2 , wherein the noise generator generates colored noise.

4. The image conversion unit as claimed in claim 3 , wherein the noise generator generates colored noise that comprises further spectral components which are in another part of the frequency spectrum which is below the Nyquist frequency of the first image, the total energy of the spectral components being higher than the total energy of the further spectral components.

5. The image conversion unit as claimed in claim 1 , wherein the amount of added noise is based on a noise measurement.

6. The image conversion unit as claimed in claim 1 , wherein the enhancing performed by the spatial enhancement filter results in the second image having increased perceived sharpness.

7. A method of converting a first image with a first resolution into a second image with a second resolution, the second resolution being higher than the first resolution, the method comprising acts of:

converting a first image with a first resolution into an intermediate image with a second resolution, the second resolution being higher than the first resolution;

adding noise to the intermediate image, wherein the said noise comprises spectral components that are in a part of a frequency spectrum that is above the Nyquist frequency of the first image; and

enhancing structures of the intermediate image which is based on the first image and which has the second resolution, wherein a combination of said adding noise act and said enhancing structures act forms said second image.

8. An image processing apparatus comprising:

receiving means for receiving a signal corresponding to a first image, said first image having a first resolution;

an image conversion unit for converting the first image into an intermediate image having a second resolution greater than said first resolution;

a noise adder for adding noise to the intermediate image, said noise comprising spectral components that are in a part of a frequency spectrum that is above the Nyquist frequency of the first image; and

a spatial enhancement filter for enhancing structures of said noise-added intermediate image which is based on the first image and which has the second resolution, thereby forming a second image.

9. The image processing apparatus as claimed in claim 8 , further comprising a display device for displaying the second image.

10. The image processing apparatus as claimed in claim 9 , wherein the image processing apparatus is a TV.