It appears that this is a very complex PDF. Its purpose is to test color digital presses, so I guess the color encoding is very fine-tuned. As I look at other objects inside the PDF I see some functions which have /Decode entries similar to what you wrote. Of course, it's kind of hard to work backwards from objects to see exactly how they're being used, so I can't say for sure that the images are using these functions.
If it means anything to you, these are the functions:
46 0 obj
<</Length 147/FunctionType 0/Filter/FlateDecode/Encode[0 63]/BitsPerSample 8/Domain[0 1]/Size[64]/Range[0 1 0 1 0 1 0 1]/Decode[0 1 0 1 0 1 0 1]>>
47 0 obj
<</FunctionType 3/Encode[0 1]/Domain[0 1]/Functions[46 0 R]/Bounds[]>>
48 0 obj
<</ColorSpace/DeviceCMYK/Coords[0 0 0 0 0 1]/Function 47 0 R/Extend[true true]/ShadingType 3>>
Here's a hex dump of the stream for object 46 0:
Code:
FF 00 FF 00 FE 00 FE 00 FC 00 FC 00 FA 00 FA 00 ÿ.ÿ.þ.þ.ü.ü.ú.ú.
F8 00 F8 00 F6 00 F6 00 F4 00 F4 00 F2 00 F2 00 ø.ø.ö.ö.ô.ô.ò.ò.
EF 00 EF 00 EC 00 EC 00 EA 00 EA 00 E7 00 E7 00 ï.ï.ì.ì.ê.ê.ç.ç.
E4 00 E4 00 E1 00 E1 00 DD 00 DD 00 DA 00 DA 00 ä.ä.á.á.Ý.Ý.Ú.Ú.
D7 00 D7 00 D3 00 D3 00 D0 00 D0 00 CC 00 CC 00 ×.×.Ó.Ó.Ð.Ð.Ì.Ì.
C9 00 C9 00 C5 00 C5 00 C1 00 C1 00 BE 00 BE 00 É.É.Å.Å.Á.Á.¾.¾.
BA 00 BA 00 B6 00 B6 00 B2 00 B2 00 AE 00 AE 00 º.º.¶.¶.².².®.®.
AA 00 AA 00 A6 00 A6 00 A1 00 A1 00 9D 00 9D 00 ª.ª.¦.¦.¡.¡...
99 00 99 00 94 00 94 00 90 00 90 00 8C 00 8C 00 ™.™.”.”...Œ.Œ.
87 00 87 00 83 00 83 00 7E 00 7E 00 79 00 79 00 ‡.‡.ƒ.ƒ.~.~.y.y.
75 00 75 00 70 00 70 00 6B 00 6B 00 67 00 67 00 u.u.p.p.k.k.g.g.
62 00 62 00 5D 00 5D 00 58 00 58 00 53 00 53 00 b.b.].].X.X.S.S.
4E 00 4E 00 49 00 49 00 44 00 44 00 3F 00 3F 00 N.N.I.I.D.D.?.?.
3A 00 3A 00 35 00 35 00 30 00 30 00 2A 00 2A 00 :.:.5.5.0.0.*.*.
25 00 25 00 20 00 20 00 1B 00 1B 00 15 00 15 00 %.%. . .........
10 00 10 00 0A 00 0A 00 05 00 05 00 00 00 00 00 ................
The other two objects don't have streams.
I never studied functions very closely in Abode's PDF reference. Maybe I should....
(EDIT: These aren't the
only functions in the PDF; I just posted a sample of three that seem to relate to each other.)