In kabouiks spirit i would advise to use gimp in ubu-chroot Sure kidding, it is quite unusable without mouse. Imagemagick was ported by NielDK. And we have 3 photo editors/effect tools on sailfish, PhotoFunia (in Jolla store), ImageWorks and DiyImg. But since the splashscreen needs to be bmp 24bit i use the gimp on desktop so i can easily output to correct format.