Originally posted by ewig
i like to try this program , but it seem just the number that's come out... how to use it ?
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ImpulseAdventure - JPEG Quality Comparison
In the first instance the things to look for are the luminance and chrominance quality factors (nearer to 100 is better) and the chroma subsampling (1x1 best 2x2 worst).
For example :
*** Marker: DQT (xFFDB) ***
Define a Quantization Table.
OFFSET: 0x00005678
Table length = 132
----
Precision=8 bits
Destination ID=0 (Luminance)
DQT, Row #0: 1 1 1 1 1 2 3 4
DQT, Row #1: 1 1 1 1 2 3 4 3
DQT, Row #2: 1 1 1 1 2 3 4 3
DQT, Row #3: 1 1 1 2 3 5 5 4
DQT, Row #4: 1 1 2 3 4 7 6 5
DQT, Row #5: 1 2 3 4 5 6 7 6
DQT, Row #6: 3 4 5 5 6 7 7 6
DQT, Row #7: 4 6 6 6 7 6 6 6
Approx quality factor = 96.95 (scaling=6.11 variance=1.09)
----
Precision=8 bits
Destination ID=1 (Chrominance)
DQT, Row #0: 1 1 1 3 6 6 6 6
DQT, Row #1: 1 1 2 4 6 6 6 6
DQT, Row #2: 1 2 3 6 6 6 6 6
DQT, Row #3: 3 4 6 6 6 6 6 6
DQT, Row #4: 6 6 6 6 6 6 6 6
DQT, Row #5: 6 6 6 6 6 6 6 6
DQT, Row #6: 6 6 6 6 6 6 6 6
DQT, Row #7: 6 6 6 6 6 6 6 6
Approx quality factor = 96.99 (scaling=6.01 variance=0.24)
*** Marker: SOF0 (Baseline DCT) (xFFC0) ***
OFFSET: 0x000058A2
Frame header length = 17
Precision = 8
Number of Lines = 3104
Samples per Line = 4672
Image Size = 4672 x 3104
Raw Image Orientation = Landscape
Number of Img components = 3
Component[1]: ID=0x01, Samp Fac=0x21 (Subsamp 1 x 1), Quant Tbl Sel=0x00 (Lum: Y)
Component[2]: ID=0x02, Samp Fac=0x11 (Subsamp 2 x 1), Quant Tbl Sel=0x01 (Chrom: Cb)
Component[3]: ID=0x03, Samp Fac=0x11 (Subsamp 2 x 1), Quant Tbl Sel=0x01 (Chrom: Cr)