使用imagemagick高质量转换图像

Question

I want to remove spots from the image shown below. I have tried using Imagemagick's convert function, but the black spots are not removed. I need a cleaner image with bold date showing.

Answer 1

In Imagemagick, you can remove the spots using connected components and optionally morphology. For example the following removes 2 pixel isolated spots or less. The morphology fills in some of the dark part of the text (it removes or opens the white background). But it may make some of the characters merge (touch):

Input:

convert spots.png \
-threshold 1% -type bilevel \
-define connected-components:area-threshold=2 \
-define connected-components:mean-color=true \
-connected-components 4 \
spots_clean.png

convert spots.png \
-threshold 1% -type bilevel \
-define connected-components:area-threshold=2 \
-define connected-components:mean-color=true \
-connected-components 4 \
-morphology open diamond:1 \
spots_clean_o1.png

convert spots.png \
-threshold 1% -type bilevel \
-define connected-components:area-threshold=2 \
-define connected-components:mean-color=true \
-connected-components 4 \
-morphology open octagon:1 \
spots_clean_o2.png