The Open Source version of PhotoShop is GIMP. If you are proficient with PhotoShop you might have a hard time getting to re-learn everything since it does things differently (sometimes harder, sometimes easier). With GIMP you can do amazing things with images.
GIMP is an advanced picture editor. You can use it to edit, enhance, and retouch photos and scans, create drawings, and make your own images. Lots of tools are available; you can sharpen and resize photos, and remove dust and red-eyes, for example.
It has a large collection of professional-level editing tools and filters, similar to the ones you might find in PhotoShop. Numerous fine-control settings and features like layers, paths, masks, and scripting give you total control over your images.
Many image file formats are supported, including JPEG, PhotoShop (.psd), and Paint Shop Pro (.psp) files. It can also be used to scan and print photos.
But this is mainly for editing images (as is PhotoShop) and putting them after one another (but that is not a movie but a slideshow).
If you are talking about movies then Blender might be what you are looking for.
Blender is an integrated 3d suite for modelling, animation, rendering, post-production, interactive creation and playback (games). Blender has its own particular user interface, which is implemented entirely in OpenGL and designed with speed in mind. Python bindings are available for scripting; import/export features for popular file formats like 3D Studio and Wavefront Obj are implemented as scripts by the community. Stills, animations, models for games or other third party engines and interactive content in the form of a standalone binary are common products of Blender use.
Some external links to video's where someone used HDR images to create movies and/or recorded a movie with HDR: