The MPlay file open dialog has extra controls for opening image sequences:
Image Size menu
You can load sequences at natural, 75%, 66%, 50%, 33%, 25%, or Custom resolution. This lets you work with smaller, faster representations of very large images.
Lock Image Size
Selecting sequences does not overwrite the custom image size fields (Image Size ▸ Custom). Normally the fields automatically update with the resolution of the selected sequence.
Single Image / Image Sequence Menu
Sequences are normally interpreted as Single Images if there is no frame number in the filename, otherwise they are interpreted as an Image Sequence. This menu allows you to manually choose which type to open.
Frame Range and Step
The frame range and frame step to load from a sequence. You can use this to load a subrange of a sequence, and/or every nth frame, to save space.
Lock Frame Range
The Frame Range fields do automatically update when you select a sequence.
Frame rate of the selected sequence. The initial value is Houdini’s global frame rate.
Flip Image Vertically
Flips loaded images vertically.
Allow Caching of This Sequence
Caches the sequence for quicker playback.