Posted: Tue Jul 01, 2008 5:20 pm Post subject: Resolution of OS data used in Memory Map
I am trying to find out what the highest print resolution that the OS data used in Memory Map supports. Or in other words, what is the highest print resolution that can be used, above which produces no improvement in actual print sharpness?
I currently use an HP Business Inkjet 2800, which supposedly supports up to 4800 by 1200 Dots Per Inch (DPI). However, once the DPI setting in the printer dialogue box is set to 600, actual print resolution when printing from Memory Map seems to have reached a limit, ie setting DPI to greater than 600 does not produce any noticable improvement. So this seems the best that I can achieve, but although quite usable, the resulting print sharpness/resolution falls very substantially short of an actual physical 25k OS map (printed on professional printers).
Just how close to the resolution / sharpness of a purchased physical 25k OS map should it be possible to achieve? There is no point in trying to buy a better printer if the source OS data used by Memory Map is of relatively low resolution.
Any views or information much appreciated. I have registered on the Memory Map Forum site, but have not received any registration back yet, so I cannot yet ask them directly.
Joined: Jun 19, 2006 Posts: 203 Location: Sahrf Lunnon ;)
Posted: Tue Jul 01, 2008 11:16 pm Post subject:
From the memory map help files... wrote:
(IMAGE showing a dialogue box noting resolution at 450dpi)
(snippety snip snip snip)
Large format printers
Notes: Printing larger than tabloid size (13x19 inches) requires a Memory-Map Professional license.
However, Ordnance Survey maps of Great Britain are limited a size of 8" by 11", whether or not you have a Memory-Map Professional license. This is due to Ordnance survey license restrictions. Check the copyright and/or license from your cartography publisher to see whether they restrict your use of the Print function.
Note that the Memory Map system will therefore NOT allow you to print anything larger than 13x19 inches in one go, whatever resolution you select. I'd also point out that while the Human eye is technically supposed to be able to resolve up to 600 dpi unaided, 300 dpi is more than adequate for most activities on paper, and your PC screen resolution is no more than 75dpi, even on an HD monitor. The stupendously high resolution of modern printing technology is therefore pretty much wasted on us mere flesh-and-blood creatures ;) _________________ Roger, G1LIW
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I have to disagree with the previous poster, at least if G1LIW meant that Memory Map produces something that effectively can't be bettered by the folded OS maps. It is very clear indeed that the folded OS maps are much sharper and clearer than the 600DPI print out I am getting from Memory Map.
As I indicated in my previous post, the MM printouts are of course entirely usable, and I have in the past year very successfully used about 15 different printed sheets, on various walks in the Dales, Peak District and Lake District. And they are far more convenient than struggling with the full folded maps, which is why I use them. I also print them on waterproof paper, which is really very durable and works well. (This appears to have no effect on the sharpness compared to printing on normal paper.)
However it is quite clear, when examining the map even by eye, and very obviously when using a magnifying glass (on my compass) as most people normally have to do to sort out complex and close detail, that the folded OS maps are far sharper and therefore clearer. Just get an example of a folded 25k OS map and a MM printed version of the same area in front of you and actually look at them both, and the difference is obvious. And I can say, from real experience on the hill, that the clarity of detail on the folded OS maps is something I would really like to be able to reproduce on printouts from MM.
So my question stands: is it possible to match the folded OS maps in print quality?
Joined: 11/07/2002 14:36:40 Posts: 23699 Location: Hampshire, UK
Posted: Wed Jul 02, 2008 9:04 am Post subject:
Surely this is due more to the limitations of consumer printers? The claimed resolutions of home printers will never match those of a commercial printer. _________________ Darren Griffin - Editor I ran the 2013 London Marathon in support of the National Autistic Society see here.
Joined: Mar 28, 2007 Posts: 129 Location: South Manchester
Posted: Wed Jul 02, 2008 9:37 am Post subject:
You can very easily determine the effective DPI of the maps (don't forget they are only bitmaps) by scaling in in memory map until the bitmap pixels are displayed at 1:1 and then measuring a feature on screen and comparing it to a feature on the paper map.
Doing this with 1:25k maps I get the maps when printed at 1:1 (i.e 1:25k scale) are 130 DPI
There's no reason not to assume that MM uses the same data as OS 1:25k Scale Colour Raster. Technical information for this states it is 254 dpi and comparing a MM 1:25k map detail (lines and text) with another map at the same scale but converted to different resolutions seems to confirm this - it's a lot better than 100 dpi, similar to 200 dpi and definitely not as good as 300 dpi.
If you classify an OS printed map detail as "line art", then the resolution should be at least 1200 dpi.
"is it possible to match the folded OS maps in print quality?" - No
Joined: Jan 14, 2005 Posts: 19636 Location: Blackpool , Lancs
Posted: Thu Jul 03, 2008 6:51 am Post subject:
There is also the issue of file size to consider here, the maps when displayed on a PC, PPC or SmartPhone are fine, when printed they are useable (but I only want them as a backup). What I really wouldn't like are maps supplied at 1200 DPI, the extra file size would make the use on mobile devices some what difficult - Mike
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