Image processing device and method

An image processing device comprising:

• a reconstructed image generation unit that reconstructs an image with a bit depth of N using an index image with a bit depth of N generated by generating histogram indicating occurrence frequency of each pixel value of the image with a bit depth of N, generating a table listing pixel values of which occurrence frequency in the generated histogram is equal to or more than one, reordering an arrangement of values in the histogram using the generated table, updating the generated table and the reordered histogram, and using the updated table and the updated histogram, and the updated table;
• and
• an upper layer image generation unit that separates the index image with a bit depth of N into an upper layer index image with a bit depth of M and a lower layer index image with (N−M) bits and reconstructs the image with a bit depth of N using the index image with a bit depth of M and the updated table.

An image processing method of an image processing device comprising:

• reconstructing an image with a bit depth of N using an index image with a bit depth of N generated by generating histogram indicating occurrence frequency of each pixel value of the image with a bit depth of N, generating a table listing pixel values of which occurrence frequency in the generated histogram is equal to or more than one, reordering an arrangement of values in the histogram using the generated table, updating the generated table and the reordered histogram, and using the updated table and the updated histogram, and the updated table, by a reconstructed image generation unit;
• and
• separating the index image with a bit depth of N into an upper layer index image with a bit depth of M and a lower layer index image with (N−M) bits and reconstructing the image with a bit depth of N using the index image with a bit depth of M and the updated table, by an upper layer image generation unit.