Enhancing pigmentation in dermoscopy images
Methods and apparatuses are disclosed for modifying images of skin so as to reduce or enhance the appearance of component pigments, such as melanin and hemoglobin. A diffuse reflectance image of skin, such as a cross-polarized contact dermoscopy image, which conveys information regarding subsurface features of the skin, is processed so as to extract pigment distribution information, which is then used to correct the diffuse reflectance image, such as by reducing the appearance of melanin to allow better visualization of hemoglobin-related structures, such as vasculature. Alternatively, the diffuse reflectance image can be corrected so as to reduce the appearance of hemoglobin to allow better visualization of melanin-related structures.
1. A method performed by a skin imaging apparatus comprising:
obtaining a diffuse reflectance image of an area of skin, including:
illuminating the area of skin with polarized light of a first orientation, and
capturing the image through a polarized filter of a second orientation, wherein the first and second orientations are mutually orthogonal;
determining a pigment component of the image, the pigment component being representative of a pigment in the area of skin;
estimating a pigment absorption distribution in accordance with the pigment component, including generating a pigment absorption distribution image in accordance with spectro-colorimetric light absorption properties of the pigment;
modifying the image by reducing or enhancing the appearance of the pigment in the image in accordance with the pigment absorption distribution, including blending the image with the pigment absorption distribution image; and
causing the modified image to be displayed, stored, transmitted or further processed.
2. The method of claim 1 , comprising:
pre-processing the image before determining the pigment component.
3. The method of claim 1 comprising:
receiving user input indicating an extent of reducing or enhancing the appearance of the pigment component in the image,
wherein the image is modified in accordance with the extent indicated.
4. The method of claim 1 , wherein the pigment includes melanin or hemoglobin.
5. The method of claim 1 , wherein:
determining the pigment component includes determining a concentration of the pigment; and
estimating the pigment absorption distribution includes determining a color of the pigment in accordance with the concentration of the pigment.
6. The method of claim 1 , wherein determining the pigment component includes at least one of the following: a color space transformation, a Red/Brown/X transformation, an Independent Component Analysis, and a Principal Component Analysis.
7. A non-transitory computer-readable storage medium having stored thereon a computer program comprising instructions for causing the skin imaging apparatus to perform the method of claim 1 .
8. A skin imaging apparatus comprising:
an image capture device including:
a light source for illuminating an area of skin with polarized light of a first orientation, and
a polarized filter of a second orientation through which a diffuse reflectance image of the area of skin can be captured, wherein the first and second orientations are mutually orthogonal;
a storage device configured to contain instructions; and
a processor configured to execute the instructions to:
obtain the diffuse reflectance image of the area of skin;
determine a pigment component of the image, the pigment component being representative of a pigment in the area of skin;
estimate a pigment absorption distribution in accordance with the pigment component, including generating a pigment absorption distribution image in accordance with spectro-colorimetric light absorption properties of the pigment;
modify the image by reducing or enhancing the appearance of the pigment in the image in accordance with the pigment absorption distribution, including blending the image with the pigment absorption distribution image; and
cause the modified image to be displayed, stored, transmitted or further processed.
9. The apparatus of claim 8 , wherein the processor is configured to execute instructions to:
pre-process the image before determining the pigment component.
10. The apparatus of claim 8 , wherein the processor is configured to execute instructions to:
receive user input indicating an extent of reducing or enhancing the appearance of the pigment component in the image,
wherein the image is modified in accordance with the extent indicated.
11. The apparatus of claim 8 , wherein the pigment includes melanin or hemoglobin.
12. The apparatus of claim 8 , wherein:
determining the pigment component includes determining a concentration of the pigment; and
estimating the pigment absorption distribution includes determining a color of the pigment in accordance with the concentration of the pigment.
13. The apparatus of claim 8 , wherein the processor is configured to execute instructions to determine the pigment component by at least one of the following: a color space transformation, a Red/Brown/X transformation, an Independent Component Analysis, and a Principal Component Analysis.
14. The method of claim 1 , wherein:
determining the pigment component includes determining a concentration of the pigment,
estimating the pigment absorption distribution includes generating a pigment absorption distribution image, including setting a color of the pigment in the pigment absorption distribution image in accordance with the concentration of the pigment, and
modifying the image includes combining the image with the pigment absorption distribution image.
15. The apparatus of claim 8 , wherein:
determining the pigment component includes determining a concentration of the pigment,
estimating the pigment absorption distribution includes generating a pigment absorption distribution image, including setting a color of the pigment in the pigment absorption distribution image in accordance with the concentration of the pigment, and
modifying the image includes combining the image with the pigment absorption distribution image.