Glyph vs. Inter

Glyph

A Glyph is nothing more than a set of foreground (black) pixels in a sheet binary image.

It carries no shape.

It is not related to a staff. It does not even belong to a system. The reason is there is no reliable way to assign a glyph located in the “gutter” between two systems or two staves: does it belong to the upper or the lower system/staff?

These restrictions on Glyph don’t apply to glyph interpretations (a.k.a. Inter).

Inter

An interpretation, or Inter for short, is meant to formalize one reasonable interpretation of a Glyph.

There may be several reasonable interpretations for a given glyph and, in many cases, the OMR engine cannot immediately decide on the right interpretation among these mutually exclusive interpretations. This decision will then be postponed until later down in the OMR process, when additional information (such as the discovery of other Inter instances located nearby) becomes available and helps clarify the configuration.

As opposed to a Glyph, an Inter belongs to a system and is often related to a staff.

It carries a shape and a grade in [0..1] range, which can be considered as the probability for the interpretation to be a true positive.
This grade is an interpretation intrinsic grade, only based on the glyph at hand in isolation (this grade is often provided by the glyph classifier).

Later, the Inter will generally be assigned a contextual grade, based on the Inter intrinsic grade and the supporting relations with other Inter instances nearby.

Typical display example

View	Inter over Glyph
	Here we have a Treble Clef Inter displayed in dark blue. Its related Glyph, using pale blue and pink colors, is mostly hidden behind.