Segmentation of black ink and melanin in skin histopathological images

The black ink (India ink) and melanin are substances often found in histopathological images of skin specimens. If present in abundant quantity, they negatively affect the outcome of automatic stain deconvolution methods. We propose an automatic black ink and melanin segmentation method based on global color thresholding in CIELAB color space combined with a novel region growing approach. Our technique achieved sensitivity of 87 %, specificity of 99 %, and precision of 94 % for black ink detection. It segmented melanin with sensitivity of 93 %, specificity of 99 %, and precision of 84 %. When excluding certain regions of images before performing color deconvolution, we observed better approximation of the stain unmixing matrix.