GNU Image Manipulation Program Formula was removed
Last versions were
gimp requires the following formulae to be installed:
pkg-config 0.29.2 Manage compile and link flags for libraries
gettext GNU internationalization (i18n) and localization (l10n) library
intltool 0.51.0 String tool
babl 0.1.46 Dynamic, any-to-any, pixel format translation library
fontconfig 2.12.6 XML-based font configuration API for X Windows
pango 1.42.1 Framework for layout and rendering of i18n text
gtk-mac-integration 2.0.8_2 Integrates GTK macOS applications with the Mac desktop
cairo 1.14.12 Vector graphics library with cross-device output support
pygtk 2.24.0_2 GTK+ bindings for Python
glib 2.56.1 Core application library for C
gdk-pixbuf 2.36.12 Toolkit for image loading and pixel buffer manipulation
freetype 2.9 Software library to render fonts
xz 5.2.3 General-purpose data compression with high compression ratio
dbus 1.12.4 Message bus system, providing inter-application communication
aalib 1.4rc5_1 Portable ASCII art graphics library
librsvg 2.42.2_2 Library to render SVG files using Cairo
libpng 1.6.34 Library for manipulating PNG images
libwmf Library for converting WMF (Window Metafile Format) files
libtiff 4.0.9_3 TIFF library and utilities
ghostscript 9.23 Interpreter for PostScript and PDF
poppler 0.64.0 PDF rendering library (based on the xpdf-3.0 code base)
libexif 0.6.21 EXIF parsing library

Recent formula history

Anastasia Sulyagina gimp: migrate to Homebrew Cask.
Uladzislau Shablinski gimp: revision for dbus rename
Viktor Szakats gimp: use secure urls
Dominyk Tiller gimp: vendor gegl02
Tom Schoonjans gimp 2.8.16

Formula code at GitHub