Figure 1.

Comparison between super-resolved ICCS and object-based analysis on simulated data. (a) Simulated dual-color images of nuclear foci at low density (total number of foci, N = 100), assuming a random distribution of foci in each channel (uncorrelated), a 25% of foci colocalization in the two channels (colocalized) and a 25% of foci colocalizing only in a specific subportion of the image (colocalized in a zone), indicated by the dashed contour. The data were simulated with a PSF size of FWHM = 120 nm. (b) Relative distance distributions (RDDs) obtained by object-based analysis of the simulated images. (c) Simulated dual-color images of nuclear foci at high density (total number of foci, N = 2000). (d) Spatial correlation functions of the images shown in (c). Shown are the cross-correlation function (black triangles) and the single-channel autocorrelation functions (magenta dots and cyan squares) along with the corresponding fits (solid lines). (e) Local ICCS maps of the images shown in (c). The color map represents the value of parameter f_ICCS calculated on a moving subregion of 69 × 69 pixels. (f) Colocalized fraction extracted from object-based analysis of the simulated data as a function of the number of foci N. The dashed red line shows the trend for the colocalized sample when the PSF size is FWHM = 250 nm. (g) Colocalized fraction extracted by ICCS analysis of the simulated data as a function of the number of foci. (h) The value of f_ICCS extracted from the local ICCS map inside (in) and outside (out) the colocalization zone for the “colocalized in a zone” sample is compared with the value of f_ICCS in the “colocalized” sample. To see this figure in color, go online.