From 913c4998b01fa18147abdf75446ea497a45815f4 Mon Sep 17 00:00:00 2001 From: David Grigg Date: Thu, 14 Sep 2023 16:27:39 +1000 Subject: [PATCH] Fixed typo and suggested alternative process for creating red layer --- .../how-to-create-svgs-from-maps-with-several-colors.php | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/www/contribute/how-tos/how-to-create-svgs-from-maps-with-several-colors.php b/www/contribute/how-tos/how-to-create-svgs-from-maps-with-several-colors.php index 58857879..68b4df3b 100644 --- a/www/contribute/how-tos/how-to-create-svgs-from-maps-with-several-colors.php +++ b/www/contribute/how-tos/how-to-create-svgs-from-maps-with-several-colors.php @@ -22,7 +22,7 @@ require_once('Core.php');
The image open in GIMP, showing the duplicated layers.
-

Lock and hide “red-layer” and work on “black-layer”. Now we need to use the Select by Color tool (Select -> By Color) to select as much of the red as we can. To do this, I’ve zoomed in quite closely to ensure I can pick the right color and adjust the tolerance up until we can select all of the red we can see. For this image, I’ve use a tolerance of 252 (the maximum).

+

Lock and hide “red-layer” and work on “black-layer”. Now we need to use the Select by Color tool (Select -> By Color) to select as much of the red as we can. To do this, I’ve zoomed in quite closely to ensure I can pick the right color and adjust the tolerance up until we can select all of the red we can see. For this image, I’ve used a tolerance of 252 (the maximum).

The select by color function in GIMP showing the red lines selected.
@@ -30,7 +30,7 @@ require_once('Core.php');
The GIMP colorize function in action showing the red lines almost gone.
-

Now lock and hide "black-layer" and work on “red-layer” and do the opposite: use the above procedure to remove the black lines.

+

Now lock and hide "black-layer" and work on “red-layer” and do the opposite: use the above procedure to remove the black lines. Alternatively, if this is difficult, use the select color function on the red lines again and copy and paste these to a new layer, which you can name “red-copy-layer”, then delete “red-layer”.

Tip: it’s a really good idea to retain some “anchor points” at the corners of your image, the same location in each layer, so that when you vectorize, each vector will be of the same outside dimensions. The four corners of a map would be good for this. After tracing, we can remove these anchors from the red layer.

Showing a map corner copied from the black layer onto the red layer to ensure the dimensions after tracing are the same.