Figure 2
Coregistration and data-extraction. (a) Example of an H&E image with annotations drawn in freehand and the extraction mask, drawn as colored shapes. Data extracted from the green areas of the extraction mask is labelled as Non-tumor, data from the red areas as Tumor and data from the blue areas as Background. (b) Projection of the first principal component of the MSI data (PC1) for outlining the tissue. (c) Coregistration of the tissue area. Grey signifying pixels that are present in both images, white signifying pixels exclusively present in the H&E-image mask and black indicating pixels exclusively present in the MALDI image. (d,e) Illustration of the principle of extracting and labelling the spectra according to the extraction mask. A spectrum for pixels labelled as background is not shown for simplicity.
