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Picture of the Month

CUP-CH 1829

This is a picture of a rust fungus (Puccinia angelicaeedulis) on a leaf. It was collected in China in 1931 and is now stored in the Cornell Plant Pathology Herbarium. This image is a composite of 2 images made with different lighting as detailed below.  


The first image is made using transillumination. The interveinal areas of the leaf show up nicely with this lighting, but the areas of rust infection are thicker and show up as dark blotches with no detail.

The second image is made using copy lighting with diffusion. With this lighting the surface and color of the rust fungus are visable but the leaf no longer has a "stained glass window" effect.

By placing the two images on overlapping Photoshop layers and using a layer mask, the prominent parts of each image are composited into one.


Kent Loeffler, Cornell University
© Cornell University, Dept. of Plant Pathology, 2004