date:20210519

Re: [mapserver-users] anti-aliasing (was differing image size with different mapserver versions)

2021-05-19 Thread Richard Greenwood

Andreas,

Very interesting. Your Cairo driver modifications create an image the same
size as your AGG driver modification that disables AA, but with strikingly
different appearance. Links to examples below. (The examples are pretty
ugly but with some work on the styles in the map file they could
significantly be improved) I have not tested performance yet.  Again -
thank you for your suggestions.

https://greenwoodmap.com/cairo-aliased.png CAIRO/PNG ANTIALIAS=FALSE
https://greenwoodmap.com/agg-aliased.png  AGG/PNG8
renderer_scanline_bin_solid


On Wed, May 19, 2021 at 9:15 AM Eichner, Andreas - SID <
andreas.eich...@sid.sachsen.de> wrote:

> If you want to give Cairo a try, you could modify mapcairo.c like this:
>
> diff --git a/mapcairo.c b/mapcairo.c
> index 0f4cc094..d28947d6 100644
> --- a/mapcairo.c
> +++ b/mapcairo.c
> @@ -517,6 +517,12 @@ imageObj* createImageCairo(int width, int height,
> outputFormatObj *format,colorO
>
>  cairo_set_line_cap (r->cr,CAIRO_LINE_CAP_ROUND);
>  cairo_set_line_join(r->cr,CAIRO_LINE_JOIN_ROUND);
> +{
> +const char* antialias = msGetOutputFormatOption(format,
> "ANTIALIAS", "TRUE");
> +if (EQUAL(antialias, "OFF") || EQUAL(antialias, "FALSE") ||
> EQUAL(antialias, "0")) {
> +cairo_set_antialias(r->cr, CAIRO_ANTIALIAS_NONE);
> +}
> +}
>  image->img.plugin = (void*)r;
>} else {
>  msSetError(MS_RENDERERERR, "Cannot create cairo image of size %dx%d.",
>
> This adds a FORMATOPTION "ANTIALIAS" to the CAIRO/*-Drivers that defaults
> to TRUE. But when explicitly set to 0/OFF/FALSE it calls
> cairo_set_antialias() to disable it. The raster buffer created by the CAIRO
> renderer is passed to the PNG writer which enables COMPRESSION,
> PALETTE_FORCE, QUANTIZE_FORCE. So you can combine it:
>
>  OUTPUTFORMAT
>NAME "cairopng"
>DRIVER CAIRO/PNG
>MIMETYPE "image/png"
>IMAGEMODE RGB
>EXTENSION "png"
>FORMATOPTION "ANTIALIAS=FALSE"
>FORMATOPTION "QUANTIZE_FORCE=ON"
>FORMATOPTION "QUANTIZE_COLORS=256"
>FORMATOPTION "COMPRESSION=9"
>  END
>
> I used the msautotest/renderers/line_simple.map example to test and that
> crushed the resulting png from 5920 bytes down to 947 bytes.
>
> HTH, Andreas
>
> -Ursprüngliche Nachricht-
> Von: Richard Greenwood 
> Gesendet: Mittwoch, 19. Mai 2021 16:12
> An: Eichner, Andreas - SID 
> Cc: mapserver 
> Betreff: Re: [mapserver-users] anti-aliasing (was differing image size
> with different mapserver versions)
>
> Andreas,
>
> I have built a version of MapServer without AA enabled in mapagg.cpp as
> you have suggested. The reduction in file size is remarkable. In some cases
> it is 1/2 the size of a GD/GIF or an optimized AGG/PNG8. Aesthetically the
> images are pretty bad at first, but by softening the colors in the map file
> and reducing the color contrast between adjacent features I'm getting
> images that are acceptable. I will try experimenting with Cairo driver
> modifications next. Thank you very much for your suggestion and detailed
> explanation.
>
> Rich
>
> On Wed, May 19, 2021 at 5:38 AM Eichner, Andreas - SID <
> andreas.eich...@sid.sachsen.de  >
> wrote:
>
>
> What AGG does with it's sub-pixel accuracy can be viewed as
> computing the contribution of the pixels of a virtually larger image to the
> pixels of the final image. It uses a gamma function to translate the amount
> of virtual pixels into an amount of visual impact on the final pixel - both
> expressed as a value in the range 0..1. AGG's default is a linear function
> that proportionally maps the range 0..1 onto 0..1 (i.e. y=x). MapServer
> (where applied) uses a linear gamma function that proportionally maps the
> range 0..gamma onto 0..1. All this results in intermediate color values
> giving a smoother and visually improved result as in this example:
> https://commons.wikimedia.org/wiki/File:Antialiasing.png#/media/Datei:Antialiasing.png
>
> As PNG uses lossless compression these additional information
> enlarges the resulting files. So to reduce the size of your map image files
> it's best to turn anti-aliasing off. One way is to compile a special
> version with modified typedefs in mapagg.cpp to turn AA off. With Cairo you
> could use the method cairo_set_antialias(cairo_t*, CAIRO_ANTIALIAS_NONE) to
> switch it off. But then you would loose paletted image and compression
> control.
>
> With the modified AGG you should still apply the other suggestions
> with reduced palette and maximum compression.
>
> HTH
>
>
> -Ursprüngliche Nachricht-
> Von: mapserver-users   > Im Auftrag von Richard
> Greenwood
> Gesendet: Dienstag, 18. Mai 2021 18:50
> An: mapserver  mapserver-users@lists.osgeo.org> >
> Betreff: [mapserver-users] anti-aliasing (was differing image size
> with different mapserver versions)
>
>

Re: [mapserver-users] anti-aliasing (was differing image size with different mapserver versions)

2021-05-19 Thread Steve Lime

Worth adding to main?

On Wed, May 19, 2021 at 10:15 AM Eichner, Andreas - SID <
andreas.eich...@sid.sachsen.de> wrote:

> If you want to give Cairo a try, you could modify mapcairo.c like this:
>
> diff --git a/mapcairo.c b/mapcairo.c
> index 0f4cc094..d28947d6 100644
> --- a/mapcairo.c
> +++ b/mapcairo.c
> @@ -517,6 +517,12 @@ imageObj* createImageCairo(int width, int height,
> outputFormatObj *format,colorO
>
>  cairo_set_line_cap (r->cr,CAIRO_LINE_CAP_ROUND);
>  cairo_set_line_join(r->cr,CAIRO_LINE_JOIN_ROUND);
> +{
> +const char* antialias = msGetOutputFormatOption(format,
> "ANTIALIAS", "TRUE");
> +if (EQUAL(antialias, "OFF") || EQUAL(antialias, "FALSE") ||
> EQUAL(antialias, "0")) {
> +cairo_set_antialias(r->cr, CAIRO_ANTIALIAS_NONE);
> +}
> +}
>  image->img.plugin = (void*)r;
>} else {
>  msSetError(MS_RENDERERERR, "Cannot create cairo image of size %dx%d.",
>
> This adds a FORMATOPTION "ANTIALIAS" to the CAIRO/*-Drivers that defaults
> to TRUE. But when explicitly set to 0/OFF/FALSE it calls
> cairo_set_antialias() to disable it. The raster buffer created by the CAIRO
> renderer is passed to the PNG writer which enables COMPRESSION,
> PALETTE_FORCE, QUANTIZE_FORCE. So you can combine it:
>
>  OUTPUTFORMAT
>NAME "cairopng"
>DRIVER CAIRO/PNG
>MIMETYPE "image/png"
>IMAGEMODE RGB
>EXTENSION "png"
>FORMATOPTION "ANTIALIAS=FALSE"
>FORMATOPTION "QUANTIZE_FORCE=ON"
>FORMATOPTION "QUANTIZE_COLORS=256"
>FORMATOPTION "COMPRESSION=9"
>  END
>
> I used the msautotest/renderers/line_simple.map example to test and that
> crushed the resulting png from 5920 bytes down to 947 bytes.
>
> HTH, Andreas
>
>
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Re: [mapserver-users] anti-aliasing (was differing image size with different mapserver versions)

2021-05-19 Thread Eichner, Andreas - SID

If you want to give Cairo a try, you could modify mapcairo.c like this:

diff --git a/mapcairo.c b/mapcairo.c
index 0f4cc094..d28947d6 100644
--- a/mapcairo.c
+++ b/mapcairo.c
@@ -517,6 +517,12 @@ imageObj* createImageCairo(int width, int height, 
outputFormatObj *format,colorO

 cairo_set_line_cap (r->cr,CAIRO_LINE_CAP_ROUND);
 cairo_set_line_join(r->cr,CAIRO_LINE_JOIN_ROUND);
+{
+const char* antialias = msGetOutputFormatOption(format, "ANTIALIAS", 
"TRUE");
+if (EQUAL(antialias, "OFF") || EQUAL(antialias, "FALSE") || 
EQUAL(antialias, "0")) {
+cairo_set_antialias(r->cr, CAIRO_ANTIALIAS_NONE);
+}
+}
 image->img.plugin = (void*)r;
   } else {
 msSetError(MS_RENDERERERR, "Cannot create cairo image of size %dx%d.",

This adds a FORMATOPTION "ANTIALIAS" to the CAIRO/*-Drivers that defaults to 
TRUE. But when explicitly set to 0/OFF/FALSE it calls cairo_set_antialias() to 
disable it. The raster buffer created by the CAIRO renderer is passed to the 
PNG writer which enables COMPRESSION, PALETTE_FORCE, QUANTIZE_FORCE. So you can 
combine it:

 OUTPUTFORMAT
   NAME "cairopng"
   DRIVER CAIRO/PNG
   MIMETYPE "image/png"
   IMAGEMODE RGB
   EXTENSION "png"
   FORMATOPTION "ANTIALIAS=FALSE"
   FORMATOPTION "QUANTIZE_FORCE=ON"
   FORMATOPTION "QUANTIZE_COLORS=256"
   FORMATOPTION "COMPRESSION=9"
 END

I used the msautotest/renderers/line_simple.map example to test and that 
crushed the resulting png from 5920 bytes down to 947 bytes. 

HTH, Andreas

-Ursprüngliche Nachricht-
Von: Richard Greenwood  
Gesendet: Mittwoch, 19. Mai 2021 16:12
An: Eichner, Andreas - SID 
Cc: mapserver 
Betreff: Re: [mapserver-users] anti-aliasing (was differing image size with 
different mapserver versions)

Andreas,

I have built a version of MapServer without AA enabled in mapagg.cpp as you 
have suggested. The reduction in file size is remarkable. In some cases it is 
1/2 the size of a GD/GIF or an optimized AGG/PNG8. Aesthetically the images are 
pretty bad at first, but by softening the colors in the map file and reducing 
the color contrast between adjacent features I'm getting images that are 
acceptable. I will try experimenting with Cairo driver modifications next. 
Thank you very much for your suggestion and detailed explanation.

Rich

On Wed, May 19, 2021 at 5:38 AM Eichner, Andreas - SID 
mailto:andreas.eich...@sid.sachsen.de> > wrote:


What AGG does with it's sub-pixel accuracy can be viewed as computing 
the contribution of the pixels of a virtually larger image to the pixels of the 
final image. It uses a gamma function to translate the amount of virtual pixels 
into an amount of visual impact on the final pixel - both expressed as a value 
in the range 0..1. AGG's default is a linear function that proportionally maps 
the range 0..1 onto 0..1 (i.e. y=x). MapServer (where applied) uses a linear 
gamma function that proportionally maps the range 0..gamma onto 0..1. All this 
results in intermediate color values giving a smoother and visually improved 
result as in this example: 
https://commons.wikimedia.org/wiki/File:Antialiasing.png#/media/Datei:Antialiasing.png

As PNG uses lossless compression these additional information enlarges 
the resulting files. So to reduce the size of your map image files it's best to 
turn anti-aliasing off. One way is to compile a special version with modified 
typedefs in mapagg.cpp to turn AA off. With Cairo you could use the method 
cairo_set_antialias(cairo_t*, CAIRO_ANTIALIAS_NONE) to switch it off. But then 
you would loose paletted image and compression control.

With the modified AGG you should still apply the other suggestions with 
reduced palette and maximum compression.

HTH


-Ursprüngliche Nachricht-
Von: mapserver-users mailto:mapserver-users-boun...@lists.osgeo.org> > Im Auftrag von Richard 
Greenwood
Gesendet: Dienstag, 18. Mai 2021 18:50
An: mapserver mailto:mapserver-users@lists.osgeo.org> >
Betreff: [mapserver-users] anti-aliasing (was differing image size with 
different mapserver versions)

Thanks to several helpful replies to my previous thread I know that the 
increased image size between MapServer 6 with the GD driver and MapServer 7 
with the AGG driver is due to differences in anti-aliasing (and lack of) in the 
two drivers. (AGG features anti-aliasing and sub-pixel resolution 
 ).

Gamma setting from 0-1 affects the size of a filled polygon layer by a 
factor of almost 3x. But gamma has no effect on text, lines, and polygon 
outlines. So images comprised of these types of features are approximately 2x 
larger with the AGG/PNG8 driver than with the GD/GIF driver. 

Where else should I be looking to reduce my images sizes? I serve rural 
areas with poor internet so in my case,

Re: [mapserver-users] anti-aliasing (was differing image size with different mapserver versions)

2021-05-19 Thread Eichner, Andreas - SID

This should make the keyword ANTIALIAS in line styles work as expected and draw 
linestrings aliased if set to FALSE. But this works not only be adding another 
typedef. It also adds another member of that type and to use it the 
agg2Render*-methods need to selectively switch between the both according to 
the value set in the style. Currently only agg2RenderLine() does that. Others 
like agg2RenderPolygon() or agg2RenderGlyphsPath() for rendering polygons and 
text simply ignore that value and simply use the anti-aliasing one.

-Ursprüngliche Nachricht-
Von: Rahkonen Jukka (MML)  
Gesendet: Mittwoch, 19. Mai 2021 15:49
An: Eichner, Andreas - SID ; Richard Greenwood 
; mapserver 
Betreff: Re: [mapserver-users] anti-aliasing (was differing image size with 
different mapserver versions)

Hi,

Can someone say if the issue is already fixed or not by  
https://github.com/MapServer/MapServer/pull/6225/files

that adds:
typedef mapserver::renderer_scanline_bin_solid 
renderer_scanline_aliased;

Is this enough for turning antialiasing off and making png files with lots of 
linework smaller? Should/could there be something more for polygons which are 
rendered with plain fill without borderlines?

-Jukka Rahkonen-

-Alkuperäinen viesti-
Lähettäjä: mapserver-users  Puolesta 
Eichner, Andreas - SID
Lähetetty: keskiviikko 19. toukokuuta 2021 14.39
Vastaanottaja: Richard Greenwood ; mapserver 

Aihe: Re: [mapserver-users] anti-aliasing (was differing image size with 
different mapserver versions)

What AGG does with it's sub-pixel accuracy can be viewed as computing the 
contribution of the pixels of a virtually larger image to the pixels of the 
final image. It uses a gamma function to translate the amount of virtual pixels 
into an amount of visual impact on the final pixel - both expressed as a value 
in the range 0..1. AGG's default is a linear function that proportionally maps 
the range 0..1 onto 0..1 (i.e. y=x). MapServer (where applied) uses a linear 
gamma function that proportionally maps the range 0..gamma onto 0..1. All this 
results in intermediate color values giving a smoother and visually improved 
result as in this example: 
https://commons.wikimedia.org/wiki/File:Antialiasing.png#/media/Datei:Antialiasing.png

As PNG uses lossless compression these additional information enlarges the 
resulting files. So to reduce the size of your map image files it's best to 
turn anti-aliasing off. One way is to compile a special version with modified 
typedefs in mapagg.cpp to turn AA off. With Cairo you could use the method 
cairo_set_antialias(cairo_t*, CAIRO_ANTIALIAS_NONE) to switch it off. But then 
you would loose paletted image and compression control.

With the modified AGG you should still apply the other suggestions with reduced 
palette and maximum compression.

HTH


-Ursprüngliche Nachricht-
Von: mapserver-users  Im Auftrag von 
Richard Greenwood
Gesendet: Dienstag, 18. Mai 2021 18:50
An: mapserver 
Betreff: [mapserver-users] anti-aliasing (was differing image size with 
different mapserver versions)

Thanks to several helpful replies to my previous thread I know that the 
increased image size between MapServer 6 with the GD driver and MapServer 7 
with the AGG driver is due to differences in anti-aliasing (and lack of) in the 
two drivers. (AGG features anti-aliasing and sub-pixel resolution 
 ).

Gamma setting from 0-1 affects the size of a filled polygon layer by a factor 
of almost 3x. But gamma has no effect on text, lines, and polygon outlines. So 
images comprised of these types of features are approximately 2x larger with 
the AGG/PNG8 driver than with the GD/GIF driver. 

Where else should I be looking to reduce my images sizes? I serve rural areas 
with poor internet so in my case, smaller image sizes are more important than 
higher quality images.

Thanks,
Rich

-- 

Richard W. Greenwood, PLS
www.greenwoodmap.com  
___
mapserver-users mailing list
mapserver-users@lists.osgeo.org
https://lists.osgeo.org/mailman/listinfo/mapserver-users
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Re: [mapserver-users] anti-aliasing (was differing image size with different mapserver versions)

2021-05-19 Thread Richard Greenwood

Andreas,

I have built a version of MapServer without AA enabled in mapagg.cpp as you
have suggested. The reduction in file size is remarkable. In some cases it
is 1/2 the size of a GD/GIF or an optimized AGG/PNG8. Aesthetically the
images are pretty bad at first, but by softening the colors in the map file
and reducing the color contrast between adjacent features I'm getting
images that are acceptable. I will try experimenting with Cairo
driver modifications next. Thank you very much for your suggestion and
detailed explanation.

Rich

On Wed, May 19, 2021 at 5:38 AM Eichner, Andreas - SID <
andreas.eich...@sid.sachsen.de> wrote:

> What AGG does with it's sub-pixel accuracy can be viewed as computing the
> contribution of the pixels of a virtually larger image to the pixels of the
> final image. It uses a gamma function to translate the amount of virtual
> pixels into an amount of visual impact on the final pixel - both expressed
> as a value in the range 0..1. AGG's default is a linear function that
> proportionally maps the range 0..1 onto 0..1 (i.e. y=x). MapServer (where
> applied) uses a linear gamma function that proportionally maps the range
> 0..gamma onto 0..1. All this results in intermediate color values giving a
> smoother and visually improved result as in this example:
> https://commons.wikimedia.org/wiki/File:Antialiasing.png#/media/Datei:Antialiasing.png
>
> As PNG uses lossless compression these additional information enlarges the
> resulting files. So to reduce the size of your map image files it's best to
> turn anti-aliasing off. One way is to compile a special version with
> modified typedefs in mapagg.cpp to turn AA off. With Cairo you could use
> the method cairo_set_antialias(cairo_t*, CAIRO_ANTIALIAS_NONE) to switch it
> off. But then you would loose paletted image and compression control.
>
> With the modified AGG you should still apply the other suggestions with
> reduced palette and maximum compression.
>
> HTH
>
>
> -Ursprüngliche Nachricht-
> Von: mapserver-users  Im Auftrag
> von Richard Greenwood
> Gesendet: Dienstag, 18. Mai 2021 18:50
> An: mapserver 
> Betreff: [mapserver-users] anti-aliasing (was differing image size with
> different mapserver versions)
>
> Thanks to several helpful replies to my previous thread I know that the
> increased image size between MapServer 6 with the GD driver and MapServer 7
> with the AGG driver is due to differences in anti-aliasing (and lack of) in
> the two drivers. (AGG features anti-aliasing and sub-pixel resolution <
> https://en.wikipedia.org/wiki/Anti-Grain_Geometry> ).
>
> Gamma setting from 0-1 affects the size of a filled polygon layer by a
> factor of almost 3x. But gamma has no effect on text, lines, and polygon
> outlines. So images comprised of these types of features are approximately
> 2x larger with the AGG/PNG8 driver than with the GD/GIF driver.
>
> Where else should I be looking to reduce my images sizes? I serve rural
> areas with poor internet so in my case, smaller image sizes are more
> important than higher quality images.
>
> Thanks,
> Rich
>
> --
>
> Richard W. Greenwood, PLS
> www.greenwoodmap.com 
>


-- 
Richard W. Greenwood, PLS
www.greenwoodmap.com
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Re: [mapserver-users] anti-aliasing (was differing image size with different mapserver versions)

2021-05-19 Thread Rahkonen Jukka (MML)

Hi,

Can someone say if the issue is already fixed or not by  
https://github.com/MapServer/MapServer/pull/6225/files

that adds:
typedef mapserver::renderer_scanline_bin_solid 
renderer_scanline_aliased;

Is this enough for turning antialiasing off and making png files with lots of 
linework smaller? Should/could there be something more for polygons which are 
rendered with plain fill without borderlines?

-Jukka Rahkonen-

-Alkuperäinen viesti-
Lähettäjä: mapserver-users  Puolesta 
Eichner, Andreas - SID
Lähetetty: keskiviikko 19. toukokuuta 2021 14.39
Vastaanottaja: Richard Greenwood ; mapserver 

Aihe: Re: [mapserver-users] anti-aliasing (was differing image size with 
different mapserver versions)

What AGG does with it's sub-pixel accuracy can be viewed as computing the 
contribution of the pixels of a virtually larger image to the pixels of the 
final image. It uses a gamma function to translate the amount of virtual pixels 
into an amount of visual impact on the final pixel - both expressed as a value 
in the range 0..1. AGG's default is a linear function that proportionally maps 
the range 0..1 onto 0..1 (i.e. y=x). MapServer (where applied) uses a linear 
gamma function that proportionally maps the range 0..gamma onto 0..1. All this 
results in intermediate color values giving a smoother and visually improved 
result as in this example: 
https://commons.wikimedia.org/wiki/File:Antialiasing.png#/media/Datei:Antialiasing.png

As PNG uses lossless compression these additional information enlarges the 
resulting files. So to reduce the size of your map image files it's best to 
turn anti-aliasing off. One way is to compile a special version with modified 
typedefs in mapagg.cpp to turn AA off. With Cairo you could use the method 
cairo_set_antialias(cairo_t*, CAIRO_ANTIALIAS_NONE) to switch it off. But then 
you would loose paletted image and compression control.

With the modified AGG you should still apply the other suggestions with reduced 
palette and maximum compression.

HTH


-Ursprüngliche Nachricht-
Von: mapserver-users  Im Auftrag von 
Richard Greenwood
Gesendet: Dienstag, 18. Mai 2021 18:50
An: mapserver 
Betreff: [mapserver-users] anti-aliasing (was differing image size with 
different mapserver versions)

Thanks to several helpful replies to my previous thread I know that the 
increased image size between MapServer 6 with the GD driver and MapServer 7 
with the AGG driver is due to differences in anti-aliasing (and lack of) in the 
two drivers. (AGG features anti-aliasing and sub-pixel resolution 
 ).

Gamma setting from 0-1 affects the size of a filled polygon layer by a factor 
of almost 3x. But gamma has no effect on text, lines, and polygon outlines. So 
images comprised of these types of features are approximately 2x larger with 
the AGG/PNG8 driver than with the GD/GIF driver. 

Where else should I be looking to reduce my images sizes? I serve rural areas 
with poor internet so in my case, smaller image sizes are more important than 
higher quality images.

Thanks,
Rich

-- 

Richard W. Greenwood, PLS
www.greenwoodmap.com  
___
mapserver-users mailing list
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Re: [mapserver-users] anti-aliasing (was differing image size with different mapserver versions)

2021-05-19 Thread Eichner, Andreas - SID

What AGG does with it's sub-pixel accuracy can be viewed as computing the 
contribution of the pixels of a virtually larger image to the pixels of the 
final image. It uses a gamma function to translate the amount of virtual pixels 
into an amount of visual impact on the final pixel - both expressed as a value 
in the range 0..1. AGG's default is a linear function that proportionally maps 
the range 0..1 onto 0..1 (i.e. y=x). MapServer (where applied) uses a linear 
gamma function that proportionally maps the range 0..gamma onto 0..1. All this 
results in intermediate color values giving a smoother and visually improved 
result as in this example: 
https://commons.wikimedia.org/wiki/File:Antialiasing.png#/media/Datei:Antialiasing.png

As PNG uses lossless compression these additional information enlarges the 
resulting files. So to reduce the size of your map image files it's best to 
turn anti-aliasing off. One way is to compile a special version with modified 
typedefs in mapagg.cpp to turn AA off. With Cairo you could use the method 
cairo_set_antialias(cairo_t*, CAIRO_ANTIALIAS_NONE) to switch it off. But then 
you would loose paletted image and compression control.

With the modified AGG you should still apply the other suggestions with reduced 
palette and maximum compression.

HTH


-Ursprüngliche Nachricht-
Von: mapserver-users  Im Auftrag von 
Richard Greenwood
Gesendet: Dienstag, 18. Mai 2021 18:50
An: mapserver 
Betreff: [mapserver-users] anti-aliasing (was differing image size with 
different mapserver versions)

Thanks to several helpful replies to my previous thread I know that the 
increased image size between MapServer 6 with the GD driver and MapServer 7 
with the AGG driver is due to differences in anti-aliasing (and lack of) in the 
two drivers. (AGG features anti-aliasing and sub-pixel resolution 
 ).

Gamma setting from 0-1 affects the size of a filled polygon layer by a factor 
of almost 3x. But gamma has no effect on text, lines, and polygon outlines. So 
images comprised of these types of features are approximately 2x larger with 
the AGG/PNG8 driver than with the GD/GIF driver. 

Where else should I be looking to reduce my images sizes? I serve rural areas 
with poor internet so in my case, smaller image sizes are more important than 
higher quality images.

Thanks,
Rich

-- 

Richard W. Greenwood, PLS
www.greenwoodmap.com  
___
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Re: [mapserver-users] anti-aliasing (was differing image size with different mapserver versions)

Re: [mapserver-users] anti-aliasing (was differing image size with different mapserver versions)

Re: [mapserver-users] anti-aliasing (was differing image size with different mapserver versions)

Re: [mapserver-users] anti-aliasing (was differing image size with different mapserver versions)

Re: [mapserver-users] anti-aliasing (was differing image size with different mapserver versions)

Re: [mapserver-users] anti-aliasing (was differing image size with different mapserver versions)

Re: [mapserver-users] anti-aliasing (was differing image size with different mapserver versions)

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