GIMP

GIMP are almost identical to those of any other image editor: layers, alpha channels, history, selection tools, transformation, masks, blurring, etc. You can also use GIMP to convert an image format, process files by the batch, create vector images, and edit animated graphics. These features can be extended with different plugins (there are more than a hundred). GIMP can work with almost every current image format, such as BMP, GIF, JPEG, MNG, PCX, PNG, PSD, PS, PDF, TIFF, TGA, SVG, and XPM. Its segmented interface can be particularly useful, since it lets you change the layout of the windows at all times, adjusting them to your preference. You can also just use the default system, similar to that of Adobe.