Charts

[idpnd]

Originally Posted by sinbad7

Have a look at this..

Sadly it's only printed charts.. You can get the same ones from Bellingham chart printers in black and white affordably

[sinbad7]

Well!! Take a closer look,and use your imagination....

Tore

[HamishB]

Originally Posted by dacust

So, now I'll just recap what I said at the very beginning. tif2bsb requires a palette type tif. But Imagemagick convert, when converting from a RGB type image to a tif, will create a RGB type tif. When converting from a palette type image, it will create a palette type tif. So, for it to work for us, we will have to create the tif from a palette type image. Well, when converting from any image to a gif, since gif is only a palette type image, convert will create a palette type gif.

So, now you know. From a jpg, we have to convert to gif first, and then convert that to a tif so we get a palette type tif.

Hi, fwiw, another quantization method using Imagemagick and noting problems with NetPBM's equivalent, is documented here:
https://trac.osgeo.org/grass/browser..._template#L593

convert - -colors 127 -compress RLE "$OUTFILE.tif" < "$INFILE.ppm"

gif isn't needed per se; "convert -colors 127" is needed.

Hamish

[dacust]

Originally Posted by HamishB

Hi, fwiw, another quantization method using Imagemagick and noting problems with NetPBM's equivalent, is documented here:
https://trac.osgeo.org/grass/browser..._template#L593

convert - -colors 127 -compress RLE "$OUTFILE.tif" < "$INFILE.ppm"

gif isn't needed per se; "convert -colors 127" is needed.

Hamish

Going from a .jpg to .tif I used -colors 127. It does not work. It produces an RGB .tif.

However, what you have different is the "-compress RLE". What I read says this is to compress for a fax. Could be it forces it to convert to a palette? Maybe a fax uses only palette style .tif?

On the other hand, best I can tell a .ppm is a palette type image so I would expect it to work already. So the question is, will the above statement work with a .jpg as an input?

Sorry, I don't have ImageMagick on this computer so I can't easily test it.

-dan

[HappySeagull]

Colour reduction for charts...
A bit of a digression,but
Check this out,per quantization and colour reduction for charts over on imgkap thread
http://www.cruisersforum.com/forums/...tml#post667790

Md'J is right into this stuff.and might know.

[HamishB]

Originally Posted by dacust

Going from a .jpg to .tif I used -colors 127. It does not work. It produces an RGB .tif.

shrug, works for me. maybe pnmquant could help too, but see notes in the script.
I assume your output RGB .tif has been reduced to 127 colors, just without a palette?

However, what you have different is the "-compress RLE". What I read says this is to compress for a fax. Could be it forces it to convert to a palette? Maybe a fax uses only palette style .tif?

RLE (run line encoding) is just one of many forms of compression you can use with tiff files. I chose it because I don't like wasting disk space, most software supports that scheme, and AFAIR that's what BSB uses. Nothing to do with faxes beyond its heritage perhaps, and it doesn't change the data any, just the internal method of zipping it.
No idea what assumptions imagemagick makes based on it though.

On the other hand, best I can tell a .ppm is a palette type image so I would expect it to work already. So the question is, will the above statement work with a .jpg as an input?

ppm is raw rgb.

see also the man page for pnmcolormap from NetPBM tools.


Hamish

[HamishB]

from the other thread:

>convert myfile -colors 127 -depth 8 -dither None myfile.tif

Otherwise the risk is to have a tif file with 127 colors, but in 24-bit (RGB) is random depending on the type of image origin.

maybe the `-depth 8 -dither None` helps?

Hamish

[MdJ]

Originally Posted by HamishB

from the other thread:


maybe the `-depth 8 -dither None` helps?

Hamish

Hello,

-dither none or +dither explained http://www.cruisersforum.com/forums/...tml#post667790

After, the question is libbsb requiring 8-bits TIFF palette with 127 colors maximum.

Doing this with imagemagick is not so simple, -depth can be used to specify the size of 8 bits, but depth also applies to other color format.
And you can generate a TIFF file in RGB, so no color palette with only 127 colors.

With a jpg, you must first decompress the image and to specify the format and process to form the output file.

> convert original.jpg +compress +dither -type palette -depth 8 r.tif

make indexed r.tif with 256 colors in 8 bits.

> convert original.jpg +compress +dither -colors 127 r.tif
make indexed r.tif with 127 colors in 8 bits.

> convert original.jpg +compress +dither -colors 127 -type TrueColor r.tif
make r.tif with 127 colors in RGB 24bits


M'dJ

[HamishB]

Reposted here from flyspray FS#54 : Chart shading for night mode.

- Brilliant to see fullscreen mode coming in. I'd put in another vote for mapping that to F11.

- xcalib on linux is brilliant, thanks for the tip!

- I had a chance to try out bit-shifting the .kap file color tables on Marco's NZ charts: worked really well. Only caveat is that first shift gives you dusk mode, second shift gives you full night mode. Third shift probably only useful as black-hole mode.
So probably floor(value/{1,2,3,4}) as the four stages is the sweet spot?

For 255,255,255 white, instead of bit-shifting I made it red by hand. I didn't shift black,near-black.

- q&d Method: copy nz123.kap to nz123_dusk.kap and nz123_night.kap. open in vi, edit the RGB header lines; rebuild chart list.
"_d" comes before "_n" so in quilt mode they are ordered 1,2,3 so you know which ones to kick out quickly.

a sed or awk script could easily make three raster chart sets for you.

still, for non-NOAA raster charts it sure would be nice for the sunset button to do that for us.


here are my NZ color rules:

#day (orig)
RGB/1,255,255,255
RGB/2,10,10,10
RGB/3,200,0,255
RGB/4,241,185,255
RGB/5,60,190,217
RGB/6,197,235,244
RGB/7,98,171,116
RGB/8,246,200,110


#dusk     floor(value/2)
RGB/1,95,10,10
RGB/2,10,10,10
RGB/3,100,0,127
RGB/4,129,92,127
RGB/5,30,95,108
RGB/6,98,117,122
RGB/7,49,85,58
RGB/8,123,100,55


#night     floor(value/4)
RGB/1,55,0,0
RGB/2,10,10,10
RGB/3,50,0,63
RGB/4,60,46,63
RGB/5,15,47,54
RGB/6,49,58,61
RGB/7,24,42,29
RGB/8,61,50,27

cheers,
Hamish

[GPS-Marco]

Hello Hamish,

try to put in a NZ chart following palette. It works fine.

Ciao, Marco.

RGB/1,255,255,255
RGB/2,10,10,10
RGB/3,200,0,255
RGB/4,241,185,255
RGB/5,60,190,217
RGB/6,197,235,244
RGB/7,98,171,116
RGB/8,246,200,110
DAY/1,255,255,255
DAY/2,10,10,10
DAY/3,200,0,255
DAY/4,241,185,255
DAY/5,60,190,217
DAY/6,197,235,244
DAY/7,98,171,116
DAY/8,246,200,110
DSK/1,63,63,63
DSK/2,2,2,2
DSK/3,50,0,63
DSK/4,60,46,63
DSK/5,15,47,54
DSK/6,49,58,61
DSK/7,24,42,29
DSK/8,61,50,27
NGT/1,0,0,0
NGT/2,30,30,30
NGT/3,30,0,30
NGT/4,15,10,15
NGT/5,0,10,25
NGT/6,0,5,15
NGT/7,0,15,0
NGT/8,20,10,0

[sailias]

Off topic but related to charts. Has anyone tested the Pilot charts on the latest build. For some reason they dont seem to load with the latest beta build of OCPN. Tried everything including changing permissions but they just refuse to load. Clueless in Canada..

/ch

[LeaseOnLife]

works with WinXP, with and without quilting

Originally Posted by sailias

Off topic but related to charts. Has anyone tested the Pilot charts on the latest build. For some reason they dont seem to load with the latest beta build of OCPN. Tried everything including changing permissions but they just refuse to load. Clueless in Canada..

/ch

[sailias]

OK good to know. Perhaps its a linux thing. Will give her another try but so far no success. Will sheck the logs on loading to see whats going on.

/ch

[sailias]

Test: load only the pilot charts and check for rendering. Note that the scale arrows do not appear on the header bar. Secondly the charts are loaded (3) and so confirmed in the log:
-------------------------------
07:38:01 AM: Chartdb: Chart directory list follows
07:38:01 AM: Chart directory #0: /home/chris123/MyMarineCharts/Charts/extras_not_in_build/NAN08.kap
07:38:01 AM: Chart directory #1: /home/chris123/MyMarineCharts/Charts/extras_not_in_build/NAN09.kap
07:38:01 AM: Chart directory #2: /home/chris123/MyMarineCharts/Charts/extras_not_in_build/NAN10.kap
07:38:01 AM: MemoryStatus: mem_total: 2052456 kb, mem_initial: 311740 kb
---------------------------------
But nothing can be displayed. Test system Ubuntu 10.10 with latest build as of yesterday.

[sailorF54]

Originally Posted by sailias

Test: load only the pilot charts and check for rendering. Note that the scale arrows do not appear on the header bar. Secondly the charts are loaded (3) and so confirmed in the log:

Aren't you selecting A CHART instead of A DIRECTORY ?