Tag  (0028,2112) 

Type  Conditionally Required (1C) 
Keyword  LossyImageCompressionRatio 
Value Multiplicity  1n 
Value Representation  Decimal String (DS) 
Example Values 

Describes the approximate lossy compression ratio(s) that have been applied to this image.
See Section C.7.6.1.1.5.2.
Required if Lossy Image Compression (0028,2110) is "01".
The value of the "compression ratio" is encoded as a numeric value that represents the numerator of an implicit ratio in which the denominator is always one, consistent with the traditional representation in the literature.
For example, a compression ratio of 30:1 would be described with a value of 30.
The value may be an estimate (e.g., the nominal value that is supplied to the compressor), or it may be a measured value (e.g., computed by dividing the uncompressed pixel data size by the size of the compressed bit stream).
Lossy Image Compression Ratio (0028,2112) may be multivalued if successive lossy compression steps have been applied; if so, the value order shall correspond to the multiple values of Lossy Image Compression Method (0028,2114), if present.
For historical reasons, the lossy compression ratio should also be described in Derivation Description (0008,2111).