Huge image problem

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Huge image problem

rich404
Hi,
So I am working on a many years long map making project. I am using a scale of
1" to 10 miles and hand drawing it on 9x12" panels of paper. The current size of
the map is about 20 by 20 feet. This is obviously too large to see in one place,
so I have been using GIMP to panel them together in a digital file. Obviously,
this file is getting quite large. I was hoping people might have suggestions on
how to reduce the size of the file without reducing the image quality too much.
It's only going to get bigger haha. I've got no experience with vector based
programs, is that the direction I need to head?

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Re: Huge image problem

Liam R E Quin
On Sat, 2019-07-06 at 16:24 +0200, btt wrote:
>  I was hoping people might have
> suggestions on how to reduce the size of the file without reducing
> the image quality too much.

> It's only going to get bigger haha. I've got no experience with
> vector based
> programs, is that the direction I need to head?

Almost certainly. Without seeing the image it’s hard to know, but try
Inkscape with a small section, and use the trace option. Note that,
unlike in most programs, the Inkscape dialogue boxes don't go away when
you press OK, so keep an eye on the status bar to see if it changes
from One Image Selected to Path with 13,293,022 nodes (or whatever).

Then you can try path->simplify and if that doesn't change the
appearnce too much it'll be smaller.

Liam (slave ankh)


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Huge image problem

rich404
In reply to this post by rich404
>Hi,
>So I am working on a many years long map making project. I am using a
>scale of 1" to 10 miles and hand drawing it on 9x12" panels of paper.
>The current size of the map is about 20 by 20 feet. This is obviously
>too large to see in one place, so I have been using GIMP to panel them
>together in a digital file. Obviously, this file is getting quite
>large. I was hoping people might have suggestions on how to reduce the
>size of the file without reducing the image quality too much. It's
>only going to get bigger haha. I've got no experience with vector
>based programs, is that the direction I need to head?

Gimp is a bitmap (raster) editor, works in pixels not feet and inches. It can
display in feet and inches but your individual canvas (tile) depends on how it
is set up with a pixels-per inch (PPI) value.

Since you started many years ago when the default was 72 PPI the tile size might
be 864 x 648 pixels. Then file size also depends on greyscale or colour (RGB)
RGB making larger files than greyscale.

Can you give details - pixel size - grey/RGB/indexed or post one of your
individual images (a tile)

For a greyscale image one tile might be about 4 MB **in memory** so a  complete
20' x 20' image 500+ tiles might be 2 GB - look at the bottom of the Gimp window
for size in memory. Colour will be larger again. Not impossible for a modern
computer but probably slow-as-a-snail for manipulating. Obviously when saved,
the file is compressed and smaller.

Making smaller? The only way in Gimp is scale each tile down (or the whole) but
that will result in degradation of the image.

Use SVG? Inkscape can convert a raster image to a vector but it all depends on
the image. Better chance with line drawings than colour images. A vector should
be smaller than the corresponding bitmap and of course scales up and down
without loss of quality.

Stitching together in Inkscape? Never tried 500+ images before. Do not know if
practical or possible.

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Re: Huge image problem

Users mailing list
How about converting to vector directly from gimp?
https://www.google.com/search?q=convert+gimp+to+vector&ie=UTF-8&oe=UTF-8&hl=en-us&client=safari


On Sat, Jul 6, 2019 at 12:21 PM rich404 <[hidden email]> wrote:

> >Hi,
> >So I am working on a many years long map making project. I am using a
> >scale of 1" to 10 miles and hand drawing it on 9x12" panels of paper.
> >The current size of the map is about 20 by 20 feet. This is obviously
> >too large to see in one place, so I have been using GIMP to panel them
> >together in a digital file. Obviously, this file is getting quite
> >large. I was hoping people might have suggestions on how to reduce the
> >size of the file without reducing the image quality too much. It's
> >only going to get bigger haha. I've got no experience with vector
> >based programs, is that the direction I need to head?
>
> Gimp is a bitmap (raster) editor, works in pixels not feet and inches. It
> can
> display in feet and inches but your individual canvas (tile) depends on
> how it
> is set up with a pixels-per inch (PPI) value.
>
> Since you started many years ago when the default was 72 PPI the tile size
> might
> be 864 x 648 pixels. Then file size also depends on greyscale or colour
> (RGB)
> RGB making larger files than greyscale.
>
> Can you give details - pixel size - grey/RGB/indexed or post one of your
> individual images (a tile)
>
> For a greyscale image one tile might be about 4 MB **in memory** so a
> complete
> 20' x 20' image 500+ tiles might be 2 GB - look at the bottom of the Gimp
> window
> for size in memory. Colour will be larger again. Not impossible for a
> modern
> computer but probably slow-as-a-snail for manipulating. Obviously when
> saved,
> the file is compressed and smaller.
>
> Making smaller? The only way in Gimp is scale each tile down (or the
> whole) but
> that will result in degradation of the image.
>
> Use SVG? Inkscape can convert a raster image to a vector but it all
> depends on
> the image. Better chance with line drawings than colour images. A vector
> should
> be smaller than the corresponding bitmap and of course scales up and down
> without loss of quality.
>
> Stitching together in Inkscape? Never tried 500+ images before. Do not
> know if
> practical or possible.
>
> --
> rich404 (via www.gimpusers.com/forums)
> _______________________________________________
> gimp-user-list mailing list
> List address:    [hidden email]
> List membership: https://mail.gnome.org/mailman/listinfo/gimp-user-list
> List archives:   https://mail.gnome.org/archives/gimp-user-list
>
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Re: Huge image problem

Michael Schumacher
In reply to this post by rich404
Am 06.07.19 um 16:24 schrieb btt:

> Hi,
> So I am working on a many years long map making project. I am using a scale of
> 1" to 10 miles and hand drawing it on 9x12" panels of paper. The current size of
> the map is about 20 by 20 feet. This is obviously too large to see in one place,
> so I have been using GIMP to panel them together in a digital file. Obviously,
> this file is getting quite large. I was hoping people might have suggestions on
> how to reduce the size of the file without reducing the image quality too much.
> It's only going to get bigger haha. I've got no experience with vector based
> programs, is that the direction I need to head?

If you are not booked on having one file, then maybe keep the multiple
files - in fact, create even more of them, at smaller scales with less
detail - and then use something like https://leafletjs.com/ (FLOSS to
make the map interactive and zoomable?

TL;DR: Leaflet is a javascript library to create maps like on the
OpenStreetmap site. They use it, actually:
https://wiki.openstreetmap.org/wiki/Leaflet

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Michael
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Re: Huge image problem

Rick Strong-2
In reply to this post by rich404
The obvious question for me is: what do you hope to do with the finished
map? Mount it on a wall? Make it the size of a driving map? Put it in a
book? Put it on the web?

Your end use will determine how you reduce it. Don't forget that optical
processes (high resolution map making camera or scanner) may be your friend
for at least reducing the huge physical size to a working size. Film has far
greater resolution than digital.

File sizes are affected by bit depth, number of colours and resolution.

Rick S.

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