Imagemagic convert pure black to pure white11/11/2023 ![]() ![]() (Actually, threshold can be seen as an extreme case of using the color curves tool. However, the black colored texts converted from the white texts (of various font sizes) all show up as 'blurred' with vertical white lines in. ![]() ![]() After the conversion, the colored objects are preserved fine. Note how the IM green color I used in my test image is not a pure green. I used the methods described by fmw42 and anthony on GIF images with colored objects and pure white colored texts on pure black background. For finer control of the output, you can use tools like color curves, levels and contrast first to isolate the light and dark portions of the image better before thresholding. Negating Images (reversing black and white) Level Adjustment Operator (gray. Since thresholding is often somewhat of a trial-and-error process to get a result you're happy with, particularly if the source image is not very close to black-and-white already, I recommend the GUI approach if possible, but if that is not an option for whatever reason you can do it through the command line as well. Running the above command on the example image produces the result shown below. You can use a graphical tool such as GIMP to do this interactively (you'll find the tool through the main menu -> Colors -> Threshold), or you can use ImageMagick something like this: convert colored.png -threshold 75% thres_colored.png each pixel with a single bit it is either on (black) or off (white). Generally, you want to convert to grayscale first for more predictable results, but it is possible to threshold a full-color image as well. Having pure text pages is of limited use in many cases similar information can. This results in a black-and-white image from an arbitrary input image. Basically, it takes an image as an input and outputs an image that has all pixels with a value below a given threshold set to black, and all pixels the value of which is above the threshold set to white. Where 20 and 80 are the luminosity under/over which everything becomes pure black/white. New file version: magick convert input.jpg -level 20,80 output.jpg. What you want is referred to as "threshold" in image processing. With ImageMagick: In-place version: magick mogrify -level 20,80 yourfile.jpg. ![]()
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