Add the test for the image quality comparison (#14)
Add the test for the image quality comparison (#14)

This test shows the image quality difference between different image formats (e.g., tif, png, jpeg) and different libraries (e.g., openslide, PIL, Tensorflow) with different reading parameters. The experiment results indicate that TIF and PNG have the highest quality; JPEG changes a lot of pixel values when it compresses the images, but has the smallest file size. When reading/saving JPEGs using PIL(subsampling=0, quality=100)/Tensorflow(dct_method=['INTEGER_FAST', 'INTEGER_ACCURATE']), different parameters will result in different quality of images.

The experiment result gives some ideas about how to storage image data when preparing the training datasets. TIF and PNG will keep the most information of the original images.

Thanks to @dusenberrymw 's suggestions on these experiments.
dusenberrymw/deep-histopath,dusenberrymw/deep-histopath