Effects of Compression in Digital Images Used for Image Analysis

Digital image analysis programs, which are useful tools in the discovery of new drugs and in industrial photography in general, can be applied to digital images to produce quantitative data that was not readily available before. Researchers and digital imaging professionals working in any scientific discipline need to be aware that artifacts can be introduced when choosing to use compression. Compressing image files can affect both subjective image quality as well as measurements extracted with image analysis programs. We were interested in the effects of compression in digital photomicrographs of rat liver tissues, using the JPEG compression component of Adobe Photoshop and Media Cybernetics Image-Pro Plus, comparing image analysis values to a TIFF uncompressed image as the gold standard. Subjective inspection and image analysis data suggest that the two compression strengths, Adobe Photoshop 0 and Image-Pro Plus 85%, produced equivalent image quality and quantitative values to TIFF uncompressed values for nuclei counts, mean percentage nuclear area, and mean nuclear area. However, using a stronger compression strength within Image-Pro Plus (90%, 95%, 100%) resulted in poorer image quality and significantly different values from TIFF uncompressed measurements. While compression does reduce file storage needs, a systematic approach should be used to determine the point when compression artifacts begin to compromise quantitative assessment. Introduction