I tried the same commands and got the same results.
$ printf "\u2318" | convert -size 100x100 label:@- \
-font unifont-Medium command.png
Changing to the unicode for the letter G works fine though:
$ printf "\u0047" | convert -size 100x100 label:@- \
-font unifont-Medium command.png
I would post this question to the ImageMagick Discourse site to see why this is occurring. I can assist if you're unsure how to do this or proceed.
Debugging convert
You can add the -debug annotate
switch to see what convert
's up to.
Example
$ printf "\u2318" | convert -size 100x100 label:@- -font unifont-Medium -pointsize 40 -debug annotate command.png
2014-04-10T09:37:04-04:00 0:00.020 0.010u 6.7.8 Annotate convert[16619]: annotate.c/RenderFreetype/1220/Annotate
Font /usr/share/fonts/msttcorefonts/arialbd.ttf; font-encoding none; text-encoding none; pointsize 12
2014-04-10T09:37:04-04:00 0:00.020 0.010u 6.7.8 Annotate convert[16619]: annotate.c/GetTypeMetrics/798/Annotate
Metrics: text: ⌘; width: 6.375; height: 14; ascent: 11; descent: -3; max advance: 24; bounds: 0.625,0 6.78125,8; origin: 7,0; pixels per em: 12,12; underline position: -5.0625; underline thickness: 3.35938
2014-04-10T09:37:04-04:00 0:00.020 0.010u 6.7.8 Annotate convert[16619]: annotate.c/RenderFreetype/1220/Annotate
Font /usr/share/fonts/msttcorefonts/arialbd.ttf; font-encoding none; text-encoding none; pointsize 12
2014-04-10T09:37:04-04:00 0:00.020 0.010u 6.7.8 Annotate convert[16619]: annotate.c/GetTypeMetrics/798/Annotate
Metrics: text: ⌘; width: 6.375; height: 14; ascent: 11; descent: -3; max advance: 24; bounds: 0.625,0 6.78125,8; origin: 7,0; pixels per em: 12,12; underline position: -5.0625; underline thickness: 3.35938
2014-04-10T09:37:04-04:00 0:00.020 0.010u 6.7.8 Annotate convert[16619]: annotate.c/RenderFreetype/1220/Annotate
Font /usr/share/fonts/msttcorefonts/arialbd.ttf; font-encoding none; text-encoding none; pointsize 24
2014-04-10T09:37:04-04:00 0:00.020 0.010u 6.7.8 Annotate convert[16619]: annotate.c/GetTypeMetrics/798/Annotate
Metrics: text: ⌘; width: 12.75; height: 28; ascent: 22; descent: -5; max advance: 48; bounds: 1.25,0 13.5781,18; origin: 15,0; pixels per em: 24,24; underline position: -5.0625; underline thickness: 3.35938
2014-04-10T09:37:04-04:00 0:00.020 0.010u 6.7.8 Annotate convert[16619]: annotate.c/RenderFreetype/1220/Annotate
Font /usr/share/fonts/msttcorefonts/arialbd.ttf; font-encoding none; text-encoding none; pointsize 48
2014-04-10T09:37:04-04:00 0:00.020 0.010u 6.7.8 Annotate convert[16619]: annotate.c/GetTypeMetrics/798/Annotate
Metrics: text: ⌘; width: 25.5156; height: 55; ascent: 43; descent: -10; max advance: 96; bounds: 2.48438,0 27.1406,35.5; origin: 29,0; pixels per em: 48,48; underline position: -5.0625; underline thickness: 3.35938
2014-04-10T09:37:04-04:00 0:00.020 0.010u 6.7.8 Annotate convert[16619]: annotate.c/RenderFreetype/1220/Annotate
Font /usr/share/fonts/msttcorefonts/arialbd.ttf; font-encoding none; text-encoding none; pointsize 96
2014-04-10T09:37:04-04:00 0:00.020 0.020u 6.7.8 Annotate convert[16619]: annotate.c/GetTypeMetrics/798/Annotate
Metrics: text: ⌘; width: 53.0312; height: 110; ascent: 87; descent: -20; max advance: 192; bounds: 4.96875,0 54.2812,70; origin: 59,0; pixels per em: 96,96; underline position: -5.0625; underline thickness: 3.35938
2014-04-10T09:37:04-04:00 0:00.020 0.020u 6.7.8 Annotate convert[16619]: annotate.c/RenderFreetype/1220/Annotate
Font /usr/share/fonts/msttcorefonts/arialbd.ttf; font-encoding none; text-encoding none; pointsize 96
2014-04-10T09:37:04-04:00 0:00.020 0.020u 6.7.8 Annotate convert[16619]: annotate.c/GetTypeMetrics/798/Annotate
Metrics: text: ⌘; width: 53.0312; height: 110; ascent: 87; descent: -20; max advance: 192; bounds: 4.96875,0 54.2812,70; origin: 59,0; pixels per em: 96,96; underline position: -5.0625; underline thickness: 3.35938
2014-04-10T09:37:04-04:00 0:00.020 0.020u 6.7.8 Annotate convert[16619]: annotate.c/RenderFreetype/1220/Annotate
Font /usr/share/fonts/msttcorefonts/arialbd.ttf; font-encoding none; text-encoding none; pointsize 95
2014-04-10T09:37:04-04:00 0:00.020 0.020u 6.7.8 Annotate convert[16619]: annotate.c/GetTypeMetrics/798/Annotate
Metrics: text: ⌘; width: 52.0781; height: 109; ascent: 86; descent: -20; max advance: 190; bounds: 4.92188,0 53.7188,70; origin: 58,0; pixels per em: 95,95; underline position: -5.0625; underline thickness: 3.35938
2014-04-10T09:37:04-04:00 0:00.020 0.020u 6.7.8 Annotate convert[16619]: annotate.c/RenderFreetype/1220/Annotate
Font /usr/share/fonts/msttcorefonts/arialbd.ttf; font-encoding none; text-encoding none; pointsize 94
2014-04-10T09:37:04-04:00 0:00.020 0.020u 6.7.8 Annotate convert[16619]: annotate.c/GetTypeMetrics/798/Annotate
Metrics: text: ⌘; width: 51.1406; height: 108; ascent: 85; descent: -20; max advance: 188; bounds: 4.85938,0 53.1562,68; origin: 57,0; pixels per em: 94,94; underline position: -5.0625; underline thickness: 3.35938
2014-04-10T09:37:04-04:00 0:00.020 0.020u 6.7.8 Annotate convert[16619]: annotate.c/RenderFreetype/1220/Annotate
Font /usr/share/fonts/msttcorefonts/arialbd.ttf; font-encoding none; text-encoding none; pointsize 93
2014-04-10T09:37:04-04:00 0:00.020 0.020u 6.7.8 Annotate convert[16619]: annotate.c/GetTypeMetrics/798/Annotate
Metrics: text: ⌘; width: 51.1875; height: 107; ascent: 84; descent: -20; max advance: 186; bounds: 4.8125,0 52.5781,67; origin: 57,0; pixels per em: 93,93; underline position: -5.0625; underline thickness: 3.35938
2014-04-10T09:37:04-04:00 0:00.020 0.020u 6.7.8 Annotate convert[16619]: annotate.c/RenderFreetype/1220/Annotate
Font /usr/share/fonts/msttcorefonts/arialbd.ttf; font-encoding none; text-encoding none; pointsize 92
2014-04-10T09:37:04-04:00 0:00.020 0.020u 6.7.8 Annotate convert[16619]: annotate.c/GetTypeMetrics/798/Annotate
Metrics: text: ⌘; width: 50.2344; height: 106; ascent: 83; descent: -19; max advance: 184; bounds: 4.76562,0 52.0156,67; origin: 56,0; pixels per em: 92,92; underline position: -5.0625; underline thickness: 3.35938
2014-04-10T09:37:04-04:00 0:00.020 0.020u 6.7.8 Annotate convert[16619]: annotate.c/RenderFreetype/1220/Annotate
Font /usr/share/fonts/msttcorefonts/arialbd.ttf; font-encoding none; text-encoding none; pointsize 91
2014-04-10T09:37:04-04:00 0:00.030 0.020u 6.7.8 Annotate convert[16619]: annotate.c/GetTypeMetrics/798/Annotate
Metrics: text: ⌘; width: 50.2969; height: 105; ascent: 82; descent: -19; max advance: 182; bounds: 4.70312,0 51.4531,65.4688; origin: 56,0; pixels per em: 91,91; underline position: -5.0625; underline thickness: 3.35938
2014-04-10T09:37:04-04:00 0:00.030 0.020u 6.7.8 Annotate convert[16619]: annotate.c/RenderFreetype/1220/Annotate
Font /usr/share/fonts/msttcorefonts/arialbd.ttf; font-encoding none; text-encoding none; pointsize 90
2014-04-10T09:37:04-04:00 0:00.030 0.020u 6.7.8 Annotate convert[16619]: annotate.c/GetTypeMetrics/798/Annotate
Metrics: text: ⌘; width: 49.3438; height: 103; ascent: 81; descent: -19; max advance: 180; bounds: 4.65625,0 50.8906,65.4688; origin: 55,0; pixels per em: 90,90; underline position: -5.0625; underline thickness: 3.35938
2014-04-10T09:37:04-04:00 0:00.030 0.020u 6.7.8 Annotate convert[16619]: annotate.c/RenderFreetype/1220/Annotate
Font /usr/share/fonts/msttcorefonts/arialbd.ttf; font-encoding none; text-encoding none; pointsize 89
2014-04-10T09:37:04-04:00 0:00.030 0.020u 6.7.8 Annotate convert[16619]: annotate.c/GetTypeMetrics/798/Annotate
Metrics: text: ⌘; width: 48.3906; height: 102; ascent: 81; descent: -19; max advance: 178; bounds: 4.60938,0 50.3281,64; origin: 54,0; pixels per em: 89,89; underline position: -5.0625; underline thickness: 3.35938
2014-04-10T09:37:04-04:00 0:00.030 0.020u 6.7.8 Annotate convert[16619]: annotate.c/RenderFreetype/1220/Annotate
Font /usr/share/fonts/msttcorefonts/arialbd.ttf; font-encoding none; text-encoding none; pointsize 88
2014-04-10T09:37:04-04:00 0:00.030 0.020u 6.7.8 Annotate convert[16619]: annotate.c/GetTypeMetrics/798/Annotate
Metrics: text: ⌘; width: 48.4375; height: 101; ascent: 80; descent: -19; max advance: 176; bounds: 4.5625,0 49.7656,64; origin: 54,0; pixels per em: 88,88; underline position: -5.0625; underline thickness: 3.35938
2014-04-10T09:37:04-04:00 0:00.030 0.020u 6.7.8 Annotate convert[16619]: annotate.c/RenderFreetype/1220/Annotate
Font /usr/share/fonts/msttcorefonts/arialbd.ttf; font-encoding none; text-encoding none; pointsize 87
2014-04-10T09:37:04-04:00 0:00.030 0.020u 6.7.8 Annotate convert[16619]: annotate.c/GetTypeMetrics/798/Annotate
Metrics: text: ⌘; width: 47.5; height: 100; ascent: 79; descent: -18; max advance: 174; bounds: 4.5,0 49.1875,63; origin: 53,0; pixels per em: 87,87; underline position: -5.0625; underline thickness: 3.35938
2014-04-10T09:37:04-04:00 0:00.030 0.020u 6.7.8 Annotate convert[16619]: annotate.c/RenderFreetype/1220/Annotate
Font /usr/share/fonts/msttcorefonts/arialbd.ttf; font-encoding none; text-encoding none; pointsize 86
2014-04-10T09:37:04-04:00 0:00.030 0.020u 6.7.8 Annotate convert[16619]: annotate.c/GetTypeMetrics/798/Annotate
Metrics: text: ⌘; width: 47.5469; height: 99; ascent: 78; descent: -18; max advance: 172; bounds: 4.45312,0 48.625,63; origin: 53,0; pixels per em: 86,86; underline position: -5.0625; underline thickness: 3.35938
2014-04-10T09:37:04-04:00 0:00.030 0.020u 6.7.8 Annotate convert[16619]: annotate.c/RenderFreetype/1220/Annotate
Font /usr/share/fonts/msttcorefonts/arialbd.ttf; font-encoding none; text-encoding none; pointsize 86
2014-04-10T09:37:04-04:00 0:00.030 0.020u 6.7.8 Annotate convert[16619]: annotate.c/GetTypeMetrics/798/Annotate
Metrics: text: ⌘; width: 47.5469; height: 99; ascent: 78; descent: -18; max advance: 172; bounds: 4.45312,0 48.625,63; origin: 53,0; pixels per em: 86,86; underline position: -5.0625; underline thickness: 3.35938
2014-04-10T09:37:04-04:00 0:00.030 0.020u 6.7.8 Annotate convert[16619]: annotate.c/RenderFreetype/1220/Annotate
Font /usr/share/fonts/msttcorefonts/arialbd.ttf; font-encoding none; text-encoding none; pointsize 86
UPDATE #1 - Debugging further
This issue was irking me so I think I've finally figured it out. The issue is the selection of the font, and it not being able to display that particular glyph.
First off you can use this command to see which fonts you have available within convert
. So let's start there.
$ convert -list font | head -8
Path: /etc/ImageMagick/type-ghostscript.xml
Font: AvantGarde-Book
family: AvantGarde
style: Normal
stretch: Normal
weight: 400
glyphs: /usr/share/fonts/default/Type1/a010013l.pfb
...
The above shows a sample, every font has lines similar to the above. Incidentally, running this command shows we have several hundred fonts:
$ convert -list font | grep Font | wc -l
262
Next we're going to go through the task of encoding our character, \u2318
using every font we have. This sounds complicated but is fairly trivial with some well thought out one liners via Bash.
$ for i in $(convert -list font | grep Font | awk '{print $2}'); \
do convert -font $i -pointsize 36 label:⌘ ${i}.gif;done
This snippet will use a for loop to run through each font, running a modified version of your convert
command.
Now we look through the results. Many of the fonts could not display this particular glyph but several could, which would seem to indicate that it's not necessarily a bug in ImageMagick, but rather a limitation of the fonts themselves. Here's a list of the fonts that I had that could display this glyph.
- DejaVu-Sans-Bold
- DejaVu-Sans-Bold-Oblique
- DejaVu-Sans-Book
- DejaVu-Sans-Condensed-Bold
- DejaVu-Sans-Condensed-Bold-Oblique
- DejaVu-Sans-Condensed
- DejaVu-Sans-Condensed-Oblique
- DejaVu-Sans-Mono-Bold
- DejaVu-Sans-Mono-Bold-Oblique
- DejaVu-Sans-Mono-Book
- DejaVu-Sans-Mono-Oblique
- DejaVu-Sans-Oblique
- DejaVu-Serif-Bold
- DejaVu-Serif-Bold-Italic
- DejaVu-Serif-Book
- DejaVu-Serif-Condensed-Bold
- DejaVu-Serif-Condensed-Bold-Italic
- DejaVu-Serif-Condensed
- DejaVu-Serif-Condensed-Italic
- DejaVu-Serif-Italic
- FreeMono-Regular
- FreeSerif-Regular
- STIX-Math-Regular
- STIX-Regular
- VL-Gothic-regular
I visually went through the entire ~260 resulting .gif
files to determine which worked and which didn't. Here's a sample of a few of the ones that worked just so you can see them.
References
It is like when background is white, ImageMagick detects that there are only two colors — black and white — and switches to a grayscale mode of PNG, hence the ugly result:
To limit the ugliness of applying black and white to anti-aliased edges, you can disable anti-aliasing with +antialias
:
convert -density 300 -alpha remove -alpha off +antialias a.pdf 300-white.png
So now, how to prevent using the grayscale mode of PNG? Here it is:
convert -density 300 -alpha remove -alpha off a.pdf png24:300-white-24.png
Best Answer
It seems these "morphology"s are were made having a black background as a basis. Once the image is white-on-black, the transformation works. From the documentation:
Negate the colors (so that I have white on black):
Then do above transformation from the question. However, I had better results with following morphology:
Still, nice to have would be to have it work from different color schemes.