Please check some good and bad images examples:

OK

OK

OK

OK

OK

OK

OK - Characters are separated

NOT OK - Characters are not separated

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OK - Characters are separated

OK

OK

OK

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OK - The background color must be lighter than the characters color (over 50%)

OK - using The background color is dark, please invert colors option

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NOT OK - Characters must be as horizontal as possible

NOT OK - The background color must be as light as possible and in one color

NOT OK - The background color must be as light as possible and in one color

NOT OK - The background color must be as light as possible and in one color

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