DICOM allows various relationships between the pixel data and how the image should be displayed. The values here are found in element 0028,0004 and every image should have that value.
All the following are supported by DicomObjects
- Normal Monochrome image
- Higher pixel values are displayed as whiter
- Reversed Monochrome image
- Higher pixel values are displayed as blacker
- Only commonly used for CR/DR images
- 8 or 16 bits per pixel
- Palettes are stored in separate attributes
- Only commonly used for Doppler US
- The most common colour format
- Alternative colour format stored as Luminance (Y) and two chroma (R - "redness" and B- "blueness") values.
The YBR_FULL_422 photometric interpretation is commonly used with lossy JPEG data.
Each pair of pixels occupies 4 bytes, each pixel having its own luminance (Y) value, but sharing the chroma (R - "redness" and B- "blueness") values.
In theory, this is also allowed for uncompressed data, but experience shows that many cheaper viewers do not support it. In uncompressed data, the values are stored as "packed cells", as follows:
Y Y B R Y Y B R Y Y B R....
- As YBR_FULL_422 but with slightly different numerical relationship between stored and displayed values.
- Reversible Colour transformation
- Used for JPEG 2000 lossless
- Irreversible Colour transformation
- Used for JPEG 2000 lossy
- Effectively the same as YBR_FULL