Is there a medibang feature similar to gradient maps in photoshop? I know about the regular gradient tool but,, I don't think gradient maps work :o
No, MediBang Paint and FireAlpaca are dedicated to digital painting, not image/photograph manipulation - generally, you will paint any colour effects you want. If you want a free program with more Photoshop-like features, I suggest you check out GIMP, which does do gradient maps and other image manipulation.
You can quickly do a partly similar effect (a bit like using a 2-colour only gradient map) using 8-bit layer conversion, but it is fairly limited: Convert your colour layer/image to an 8-bit layer, select a layer colour, place another layer underneath filled with a flat colour.
-Obtusity















