Scanned charts

[Gordonmc]

I now have my PDA (iPaq 3660) set up for navigation using Oziexplorer P2.
The GPS side works fine, but the quality of the repro charts is a disappointment.
Tis is probably down to the way I scanned paper charts, using a Canon flat plate A4 scanner. The colours are washy and any zoom blurs detail.
The download demo for Maptech showed how good the display can look, but I need the flash card port for GPS.
Anyone have any tips as to how I can improve the quality of the images?

 

[Guest]

Be aware that scanning paper charts will be a breach of copyright.

Having said that, the problem will be that you have set the scanning resolution and the contrast incorrectly on your scanner. If you were to scan at maximum resolution, every fibre in the paper will be visible in glorious technicolour detail, and your computer will crash with the size of the file, so you don't want to do that. You on the other hand must somehow have set a miserably low scanner resolution if you can't even read the printed detail on a chart. You have to experiment between setting a scanner resolution that resolves detail without creating huge file sizes. My guess is that the same resolution as your average screen, about 72dpi, should be sufficient. A typical flatbed scanner will do around 3000dpi, which is massively more detail than you need.

Also, after you preview the scan, but before you scan, adjust the contrast setting on the scanner so the chart looks right.

 

[aidancoughlan]

there's another post today on "Free marine navigation software", which includes a link to http://www.sping.com/seaclear/ - I took a look out of curiosity, and there's a section on "How to scan charts an much more" - I dont know if your question is answered there, but may be worth a look.

 

[dick_james]

Sounds like resolution is the problem. Seaclear suggest 100 to 250 dpi. I did mine at 300 and it was more than adequate.

 

[Gordonmc]

Thanks for all replies.
I found the original scanned files and converted the bmp's back to jpg and ran them through an enhancement feature of some new software I managed to blag. By playing around I got some charts to look quite decent on the PDA, although they look over-vibrant on the PC.
I guess its a case of trial and error, but I'm pleased with the outcome.