rgdal, multiband CCITT compression

Ok, thanks. I can try later today with Manifold System, which may be. I'm
not sure of other non-GDAL tools to double check TIFFs with. (ArcGIS 10 uses
GDAL but I don't know to what extent).

Is the output above what you expect, or what you get? That's what I get.
Sorry to be dim, but I don't see where you've specified what's actually
wrong (and I haven't explored enough to see if that's easy to determine from
the code).

That's a?cunning use of formals() to?change defaults for a function?- a bit
radical for my taste, but I like it.

Cheers, Mike.

On Fri, Nov 5, 2010 at 11:00 AM, Oliver Soong <osoong+r at gmail.com> wrote:

Here's an example:




require(rgdal)
formals(paste)$sep <- ""

SP27GTIF <- readGDAL(
?system.file("pictures/SP27GTIF.TIF", package = "rgdal")[1],
?output.dim=c(100,100)
)
img_1bit_1band <- SP27GTIF
img_1bit_1band at data$band1 <- as.integer(SP27GTIF at data$band1 > 85)
img_1bit_2band <- SP27GTIF
img_1bit_2band at data <- data.frame(
?band1 = img_1bit_1band at data$band1,
?band2 = as.integer(SP27GTIF at data$band1 > 170)
)

for(img in c("img_1bit_1band", "img_1bit_2band")) {
?cat(paste("*** Correct Stats: ", img, "\n"))
?print(sapply(get(img)@data, table))
?for(compress in c("NONE", "DEFLATE", "LZW", "CCITTRLE",
? ? ? ? ? ? ? ? ? ?"CCITTFAX3", "CCITTFAX4")) {
? ?file <- paste(img, "_", compress, ".tif")
? ?writeGDAL(get(img), file, type = "Byte",
? ? ?options = c("NBITS=1", paste("COMPRESS=", compress)))
? ?cat(paste("Compression: ", compress, " from ", file, "\n"))
? ?reread <- readGDAL(file, silent = TRUE)
? ?print(sapply(reread at data, table))
?}
?cat("\n")
}





The expected output is:

*** Correct Stats: img_1bit_1band
?band1
0 ?3086
1 ?6914
Compression: NONE from img_1bit_1band_NONE.tif
?band1
0 ?3086
1 ?6914
Compression: DEFLATE from img_1bit_1band_DEFLATE.tif
?band1
0 ?3086
1 ?6914
Compression: LZW from img_1bit_1band_LZW.tif
?band1
0 ?3086
1 ?6914
Compression: CCITTRLE from img_1bit_1band_CCITTRLE.tif
?band1
0 ?3086
1 ?6914
Compression: CCITTFAX3 from img_1bit_1band_CCITTFAX3.tif
?band1
0 ?3086
1 ?6914
Compression: CCITTFAX4 from img_1bit_1band_CCITTFAX4.tif
?band1
0 ?3086
1 ?6914

*** Correct Stats: img_1bit_2band
?band1 band2
0 ?3086 ?8353
1 ?6914 ?1647
Compression: NONE from img_1bit_2band_NONE.tif
?band1 band2
0 ?3086 ?8353
1 ?6914 ?1647
Compression: DEFLATE from img_1bit_2band_DEFLATE.tif
?band1 band2
0 ?3086 ?8353
1 ?6914 ?1647
Compression: LZW from img_1bit_2band_LZW.tif
?band1 band2
0 ?3086 ?8353
1 ?6914 ?1647
Compression: CCITTRLE from img_1bit_2band_CCITTRLE.tif
?band1 band2
0 ?6131 ?8783
1 ?3869 ?1217
Compression: CCITTFAX3 from img_1bit_2band_CCITTFAX3.tif
?band1 band2
0 ?6131 ?8783
1 ?3869 ?1217
Compression: CCITTFAX4 from img_1bit_2band_CCITTFAX4.tif
?band1 band2
0 ?6131 ?8783
1 ?3869 ?1217



Everything looks fine except CCITT compression with 2 bands.

I wasn't able to dig up Windows GDAL 1.7.1 binaries, and the 1.7.0
binaries from FW_Tools seem to give similar behavior, although it's a
little hard to check because neither ArcGIS nor ENVI seems to like any
of the multi-band files.

--
Michael Sumner
Institute for Marine and Antarctic Studies, University of Tasmania
Hobart, Australia
e-mail: mdsumner at gmail.com