Fig. 1

Overview of image acquisition and processing. Digital images are composed of the three basic colors red, green, and blue (a). The observed color is determined by the bit depth of each of the three basic colors. In a first step, images were acquired for each basic color separately (b), followed by an image processing step (c) where the pixel values of the color of interest was divided by its complementary color. In our case, the red channel was divided by cyan, a mixture of green and blue. The thresholding on the bit depth was performed after this step. MSCs differentiated for 14, 17, and 21 days into osteoblasts, adipocytes, and chondroblasts were quantified (n = 3) by scanning the whole well of multi-well plates (d). DIA quantification of the staining showed a constant increase in differentiation for all three lineages (n = 3, error bars represent SD) (e). The system is very robust. Most of the background as well as other disturbing factors, such as dirt, are eliminated (f)