Consistent terminology

[chrisn]

Originally raised by @fintelia as part of #346:

A bunch of sections use different terminology, likely because they were written at different times by different people:

Section 4.2: Talks about a "source image" getting transformed into a "reference image", with the former explicitly left out of scope of the spec and the later consisting of dimensionless RGB or RGBA channels with $2^{sampledepth}$ bits.

cHRM chunk: Talks about display primaries "used" in "the image", without indicating whether that's the source image, reference image, or some other image.

sRGB chunk: Now the samples "conform" to a colour space and have a "rendering intent"

cICP and mDCv chunks: TV terminology as mentioned

Section 12.1 This section leans heavily into talking about samples being "light intensities" in an abstract 0-1 range. The concept of > "original scene intensity" is mentioned but glossed over.

transfer function definition: "image luminance", "image samples"

[ProgramMax]

Assigning to CS as discussed last meeting.

[ProgramMax]

Also adding Simon.

[chrisn]

Another one I noticed: in Table 2, for mDCV there's "eventual display" but elsewhere in the spec the same concept is "display device".