We also studied the heterogeneity of the optical properties of NDs in cell in greater detail (Figure e,f), with the help of a simple procedure. Here we acquired two FL images, with MW on-and off-resonance. Taking their difference and then normalizing pixelwise, it is possible to reconstruct an ODMR contrast image (Fig. ). In this ODMR contrast mapping, an average 4.5% contrast is observed. Moreover, parts with a high (red) and a low (blue) ODMR contrast can be imaged within the cell. These regions of low ODMR contrast correspond to cellular compartments where NDs cannot easily access, such as the nuclei. We selected a 1% contrast threshold in the ODMR mapping to cut down the noise. Therefore, wide-field ODMR mapping demonstrates the detection of NV centers in cells with a subcellular spatial resolution that is important for mapping the internalization of NDs in cellular compartments. These results pave the way for real-time, fast, and non-invasive mapping of single and ensemble of NV-enriched NDs in vivo and in vitro cellular environments.