New answers tagged anti-aliasing
Your image is not black-on-white; it's all black with variable transparency. When you tell GIMP to select only the black pixels, it will select all the pixels, except those that are fully transparent, since as far as GIMP is concerned, those pixels are all black. One way to make it work as you seem to expect (i.e. only select the pixels that are 100% ...
Under 'Tool Options' of 'Select by Color Tool' set the 'Threshold' slider to 0, it will only select exactly the same colors.
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