jpg in OpenCPN

[HappySeagull]

Originally Posted by bewitched

Always looking to streamline the process.... especially if I don't have to use that horrible Command Prompt thingy.

What's "Chartconvert". I googled, but without much luck. Do you have a link?

ta.

It's a recipe.You have to break eggs and measure teaspoons.I'm looking for a "Breadmachine" ,believe me but meanwhile,I want to eat.
There's no "click and drag"-Tada! that I've heard about...

[sinbad7]

bewitched..

Chartconvert is a great program from a fellow sailor in Germany.

All the conversion programs also need the innstallation of external progs.

Download it here: 4shared - Useful programs - shared folder - free file sharing and storage

Regds
Tore

[HappySeagull]

Originally Posted by sinbad7

bewitched..

Chartconvert is a great program from a fellow sailor in Germany.

All the conversion programs also need the innstallation of external progs.

Download it here: 4shared - Useful programs - shared folder - free file sharing and storage

Regds
Tore

Hey,good one,Tore!The 1st chart I just baked looks pretty good!
Did I say "Bread Machine"?
Bewitched,you will like this too,I bet...

[bewitched]

It just keeps getting better

Getting these charts onto a chartplotter is a really big deal for me and I really do appreciate the help I'm getting here.

One more query if I may. When I'm working with the original .jpg file, either to compress it or to get it to a palette colour .png, it runs really, really slow with the bigger files.

It's OK with .jpgs under 10MB, but over that it grinds and sometimes gives me the "not responding" message. Is this down to my computer? I have 4MB of RAM and have opened up the vitual memory to 10MB and closed as much of the background programs at the clock as possible. It made a bit of difference, but not much.

Given that I've got 200+ charts to convert, speeding up the process would be a bonus. Is this a case of having to go out and buy more RAM, or is there something else I can do?

[sinbad7]

Bewitched.

Your bitmap charts are just enormous and far bigger than any normal chart.
What is the resolution of the bitmaps? Anything over 75 dpi is a waste of space as your screen only displays around 75 dpi. Try reducing them to 150 or 75 dpi. If they cover a large area you could also split the bitmaps up to more manageable sizes. Your final charts should not be larger tan 3-7 MB.

Good luck!

Tore

[HappySeagull]

Oh,bewitched...don't get TOO giddy-I don't want to hear about you on some reef!Maybe go walkabout with one and see how good it is...after all,it's a lot of work redoing.

[bewitched]

Originally Posted by sinbad7

Bewitched.

Your bitmap charts are just enormous and far bigger than any normal chart.
What is the resolution of the bitmaps? Anything over 75 dpi is a waste of space as your screen only displays around 75 dpi. Try reducing them to 150 or 75 dpi. If they cover a large area you could also split the bitmaps up to more manageable sizes. Your final charts should not be larger tan 3-7 MB.

Good luck!

Tore

I'm getting them from here:

Office of Coast Survey's Historical Map & Chart Project Image Catalog

Search: Region = Philippine Islands.

They download as .jpg files, generally in the 20MB to 35MB file size.

would love to reduce this if I could

Edit: how do I reduce the dpi then?

[bewitched]

Originally Posted by HappySeagull

Oh,bewitched...don't get TOO giddy-I don't want to hear about you on some reef!Maybe go walkabout with one and see how good it is...after all,it's a lot of work redoing.

Heh heh heh... who told you about my reef??...

Don't worry, I'm not the head in the chartplotter type sailor.

I've had too many moments in the Philipines when it comes to what's charted and what's actually there.

I watch the depth sounder like a hawk and view the charts in the same patient manner as the bloke from the pub who told me where to find mermaids.

I look, I would like to believe, but I remain pessimistic...

[bewitched]

Originally Posted by sinbad7

Bewitched.

Your bitmap charts are just enormous and far bigger than any normal chart.
What is the resolution of the bitmaps? Anything over 75 dpi is a waste of space as your screen only displays around 75 dpi. Try reducing them to 150 or 75 dpi. If they cover a large area you could also split the bitmaps up to more manageable sizes. Your final charts should not be larger tan 3-7 MB.

Good luck!

Tore

Ah ha!! I figured this one out all by myself

DPI = dots per inch.

And Inches are a unit of measurement used in the olden days. Which is fitting, because my charts are in fathoms, and there are 72 inches in a fathom exactly....so all I need to do is divide by 72??...........

Sorry... just my terrible sense of humour running away again.

On the serious side - I did manage to reduce the no. of pixels in each direction to about 30% of what they were before and this made a huge difference in file size and no dicernable loss in picture quality.

Of course this speeded up the process no end.

Thank's all for your patience

[HappySeagull]

(But NannySeagull says!)
I'm sad you have to fiddle with the original image.This is not the best.I don't want you do have to go back and redo IF you discover a better way later.
It sounds like you found the button to reduce total size as a percentage?...?that'll keep the aspect ratio the same but it'll be a smaller image IE if you were looking at a narrow channel,the gps position icon could blot it out entirely,where on a BIG image you can happily fit between the banks and buoys...
Or did you find the button to change dpi as Sinbad was saying?

You have already figured this out-more compression doesn't decrease load on the computer,because it'll be reinflating to reproduce the original dpi and size together...ie real-estate.So avoid increasing (lossy)or decreasing (no improvement-what's gone is forever gone...)compression from the original...
anyways,my brain hurts so I'll leave you to it...

[GPS-Marco]

I tried to modify KapGen to better handle these new chart data base (NOAA historical)

Now KapGen can handle not only colours reduction and crops but also image resizing. Just download this attached alpha7 version.

You'll find 3 CHARTCAL.DIR (in Calibration) to try to show the process.

Calibration Process:

1) go the NOAA historical site HERE and find the chart you want to calibrate. Imagine to go to philippines area and that you want BAHIA LAOLAO SAIPAN AND SUNHARON ROADS TINIAN

2) append to the CHARTCAL.DIR the following text (See CHARTCAL-Phase1.DIR)

[NH81071.BMP]
NA=BAHIA LAOLAO SAIPAN AND SUNHARON ROADS TINIAN
FN=NH81071.BMP
NU=81071-4-1991
CR=BSBHDR CED/SE=1991,RE=0,ED=04/15/1991
 BSBHDR KNP/SD=MEAN LOWER LOW WATER
 MD5SUM 0
 GETMAP http://historicalcharts.noaa.gov/historical_jpgs/81071-4-1991.jpg
 IMGMOD 81071-4-1991.jpg 50 64
 WARNING! Not to be used for navigation.
 MAPCPR Sourced from NOAA Historical Charts DataBase
 CALCPR Calibration by Marco Certelli. Free for PERSONAL (non-commercial) use only.

Note that all data come from the web site (copy-paste will help you a lot...). The KNP/SD is a speculation. You can change it during calibration in MapCal.

3) Open KapGen and type NH81071. KapGen will download the jpeg and will prepare for you a BMP image to calibrate. Note that the command "IMGMOD 81071-4-1991.jpg 50 64" instructs Kapgen to resize the image to 50% and to reduce colours to 64. Do not close KapGen at the end.

4) Open MapCal, open image (go in Calibration folder and load NH81071.BMP). You will discover that this map is composed of 2 maps side by side! Unfortunately this is the most complex case!

5) close MapCal and open XnView (or any other pics viewer/handler). Open NH81071.BMP and find the optimal crop for the left side map.

6) open CHARTCAL.DIR with a Text Editor and make the following changes:

[NH81071_1.BMP]
NA=BAHIA LAOLAO SAIPAN AND SUNHARON ROADS TINIAN
FN=NH81071_1.BMP
NU=81071-4-1991_1
CR=BSBHDR CED/SE=1991,RE=0,ED=04/15/1991
 BSBHDR KNP/SD=MEAN LOWER LOW WATER
 MD5SUM 0
 GETMAP http://historicalcharts.noaa.gov/historical_jpgs/81071-4-1991.jpg
 IMGMOD 81071-4-1991.jpg 50 64 194 855 3288 4288
 WARNING! Not to be used for navigation.
 MAPCPR Sourced from NOAA Historical Charts DataBase
 CALCPR Calibration by Marco Certelli. Free for PERSONAL (non-commercial) use only.

Changes are: add _1 on [title], FN=, NU= and then add the crop data in the IMGMOD field. The numbers 194 855 3288 4288 means: crop is from pixel x=194,y=855 and the cropped image shall be 3288x4288 pixels. See the XnView lowest bar to read these data.

7) Now type in KapGen NH81071_1. KapGen now use the already downloaded file. It will resize the image, change the colours, crop the image. At last you will find the NH81071_1.BMP in the calibration folder.

8) Open MapCal, go in Calibration folder and load NH81071_1.BMP. You can now calibrate the map. At the end put the right MD5 by replacing the "0". Finally you can save calibration and shoud have something similar to CHARTCAL-Phase2.DIR

9) Type in KapGen NH81071_1. You should have the NH81071_1.kap ready to be used!

Steps 5) 6) and 7) do not apply if the chart does not need a crop. add _2 for the right side of the map... and redo calibration.

I know it's a long process, but at the end you have a tool that allows everybody to build the calibrated map you prepared. In fact I've already prepared the calibration of 2 maps: NH81071_1 and NH25673. Just try them.

I think I've to clarify many other details. Just ask me.

Ciao, Marco.

[GPS-Marco]

Sorry, the attachment did not work (maybe too large file). Here is a link to download KapGen Alpha 07

http://mce66.altervista.org/software...en-alpha07.zip

Let me know.

Ciao, Marco.

[idpnd]

Looks like an interesting project actually - you should publish the results really

[GPS-Marco]

Originally Posted by idpnd

Looks like an interesting project actually - you should publish the results really

Hello.

What do you mean with publishing the results? If you mean the NH81071_1 and NH25673 kap files, well download KapGen alpha 7, double chick on KapGen.cmd, write NH81071_1 and you get NH81071_1.kap, write NH25673 and you get NH25673.kap

But the real result is KapGen itself. Now the whole process of calibrating a jpeg once and for all can be made authomatic (well, after some volunteer has prepared the right CHARTCAL.DIR...).

Ciao, Marco.

[idpnd]

Sorry I meant calibration of the Philippine charts