How do I get text bounding box drawn with pgmagick - imagemagick

I successfully draw some text on an image by pgmagick:
from pgmagick.api import Image
img = Image((300, 200))
img.annotate('Hello World')
img.write('helloworld.png')
but how to get the bounding box of text? Anyone can help me?

I don't know anything about pgmagick but maybe it will help if I show you a couple of things you can do at the command line with ImageMagick.
Option 1
Use label to create a canvas just big enough for the desired text and then ask ImageMagick how big that canvas's geometry is:
convert label:"Hello world" -format %G info:
62x15
So, "Hello world" in the default font size is 62 pixels wide and 15 pixels high.
Option 2
Or, use -annotate as you did, and then ask ImageMagick how big that would be if you trimmed the excess space around it:
convert -size 300x200 xc:red -annotate +10+20 "Hello world" -format %# info:
61x8+10+12
Option 3
Create the canvas and annotate it, then trim it and get the size:
convert -size 300x200 xc:red -annotate +10+20 "Hello world" -trim info:
xc:red XC 61x8 300x200+10+12 16-bit sRGB 0.000u 0:00.000
Option 4
Create canvas, annotate, trim, save and then get dimensions of result:
convert -size 300x200 xc:red -annotate +10+20 "Hello world" -trim result.png
identify result.png
result.png PNG 61x8 300x200+10+12 16-bit sRGB 887B 0.000u 0:00.000
Maybe (hopefully) you can adapt one of these to pgmagick.

Related

Get geometry of text on an image

I'd like to draw a text onto an image in a way like this:
convert -quality 100 -font Oswald-Regular -pointsize 515 -fill black -draw "text 1339.0,1099 'some text'" /tmp/ascript.png /tmp/ascript.png
and I need to know the dimensions of the text with the above parameters (size, font, text). How can I get that?
I tried something like this:
convert -size 5000x1500 xc:lightblue -font Oswald-Regular -pointsize 515 -fill none -undercolor white -annotate +20+100 'some text' -trim info:
but it's giving false result:
xc:lightblue XC 1834x250 5000x1500+19+0 16-bit sRGB 0.010u 0:00.000
.
What is the proper way (or a working way) to get the dimension of a drawn image based on this 3 parameters (font, size, text)?
I'm not strictly binded to ImageMagick, it can be any command line tool for the Linux shell, however, the text will be drawn by convert.
There are a couple simple ways to get the dimensions using ImageMagick with commands like this...
convert -size 5000x1500 xc:lightblue -font Oswald-Regular -pointsize 515 \
-fill none -undercolor white -annotate +20+100 'some text' \
-format "%[#]\n" info:
That uses the FX escape "%#" as the formatting string for the "info:" output. It will show IM's calculation of the after-trim width, height, horizontal offset, and vertical offset like "WxH+X+Y".
This similar command just gives the width and height of the trimmed text...
convert -size 5000x1500 xc:lightblue -font Oswald-Regular -pointsize 515 \
-fill none -undercolor white -annotate +20+100 'some text' \
-trim +repage -format "%[w]x%[h]\n" info:
That will trim the text, reset the paging geometry with "+repage", then output a string showing "WxH".
––– Edited to Add –––
I tried your image with_text.png with these commands. The output immediately follows each command...
convert with_text.png -format "%[#]\n" info:
1807x389+512+115
convert with_text.png -trim +repage -format "%[w]x%[h]\n" info:
1807x389
Those were tested with IMv6.8.9-9 on ubuntu bash on Windows 10. If you use that actual image and those commands, I'm not sure why you would get different results.

Applying watermark on an image

I'm trying to apply watermark on an image using the following imagemagick command
convert input.png watermark.png.png -gravity northwest -composite output.png
The input png file size is 16KB and the watermark file size is 900bytes, but when I executed the above command to apply a watermark, the output png size is 61KB which is almost 4X the size of the original input png file. Is there any better way of applying a watermark to an image file with much better result in terms of output filesize
Test Image: https://res.cloudinary.com/deks86ilr/image/upload/v1533015495/1_rnpbye.png
Test watermark: https://res.cloudinary.com/deks86ilr/image/upload/v1533015494/2_usmonh.png
Here are my results of processing of your images with my PNG8 output using ImageMagick 6.9.10.8 Q16 with libpng 1.6.34.
I note that your input image was type palette, which means it is 8-bits of color per pixel and not 24-bit color. So it is already a low quality image.
Input (~16 KB):
Watermark Image (white on transparency -- so it is invisible here):
Convert to 24-bit PNG:
convert input.png watermark.png -gravity northwest -compose over -composite input_with_watermark.png
I see no significant visible quality loss but the output is now increase from 16 KB to 60 KB. But you can use tools such as pngcrush to compress it further.
Convert to 8-bit PNG:
convert input.png watermark.png -gravity northwest -compose over -composite PNG8:input_with_watermark2.png
The file size is now back to about 16 KB. But as you note the quality is a little poorer. This is likely because the input image (at 8-bits and has 217 colors) was first read back to 24-bits, then watermarked, which included new shades of white and then quantized back to 8-bits, but contains only 84 colors colors.
Another way is to add +dither -colors 256 to the command (the +dither turns off dithering):
convert 1_rnpbye.png 2_usmonh.png -gravity northwest -compose over -composite +dither -colors 256 PNG8:watermark3.png
This is a bit better, since it now uses 189 colors and still has a file size of 16 KB.
One final method is to save the colors from your input to a colortable image. Then use -remap to recolor the output using that colortable:
convert 1_rnpbye.png -unique-colors colortable.gif
convert 1_rnpbye.png 2_usmonh.png -gravity northwest -compose over -composite +dither -remap colortable.gif PNG8:watermark4.png
This results in 8-bit output with 227 colors and still a file size of about 16 KB. So it has a few more colors than your input and visually looks about the same quality as your input.
If you cannot reproduce these results, then perhaps you should upgrade either or both ImageMagick and libpng.

Create blank image in Imagemagick

How to create a blank new image in Imagemagick via command line?
Using -background doesn't work:
$ convert -size 800x800 -background white x.png
convert: no images defined `x.png' # error/convert.c/ConvertImageCommand/3257.
White background
convert -size 800x800 xc:white white.png
xc: used to mean "X Constant Image" but now is just a shorthand for canvas:. This means you can also use:
convert -size 800x800 canvas:white white.png
and because "white" is the default value if no color is provided, you can also use:
convert -size 800x800 xc: white.png
convert -size 800x800 canvas: white.png
Transparent background
If by "blank" you mean "transparent", just use that word as the color:
convert -size 800x800 xc:transparent transparent.png
Answer made possible by ImageMagick v6 Examples and How to create a new image?
You need to supply PNG24, PNG8 or PNG32 prefix if planning to use this canvas to layer colour images over. Without it, it creates a Grey colour space. I used 32, as I need "varying degrees of transparency for each pixel" (pixel art)
convert -size 800x800 canvas:transparent PNG32:canvas.png
For more about PNG types see this link.

How to convert gray scale png image to RGB from comand line using image magick

I am trying to convert an png Gray scale image to RGB png image using the following command.
convert HopeLoveJoy.png -size 1x1 -fill "rgba(0%,1%,2%,0)" -draw "color 511,511 point" out_test.png
By using the above the above command I am able to convert but the color of the image is getting changed.
Is any thing wrong in the command??
Any help is appreciated.
Thanks in advance.
If, as your question title implies, you really just want to go from greyscale to sRGB colorspace, use this:
convert image.png -define png:color-type=2 result.png
I check it like this:
convert image.png -define png:color-type=2 result.png && identify -format "%[colorspace]" result.png
sRGB

How to output white png version of my image ?**

With ImageMagick shell command (convert?)...
Given a colorful input.png image.
How to us input.png to produce a white output.jpg version with similar dimensions an opacity of 100% ?
I will later on use this layer in my workflow.
This should work:
convert input.png -threshold -1 output.jpg
This transforms any pixel with an intensity greater than (-1), i.e., all of them, to white.
It does not work with GraphicsMagick, though, because in GM the threshold value is unsigned (in ImageMagick it's a signed "double"). Neither of the applications documents exactly what is supposed to happen when the threshold is negative.
Here's a command that works on both ImageMagick and GraphicsMagick, and is documented:
[gm] convert input.png -fuzz 100% -fill white -opaque gray output.jpg
You could use fill, like this:
convert input.png -fill "#ffffff" output.jpg
or
convert input.png -fill white output.jpg
Or you can convert all three channels (red, green and blue) to "1" which is full intensity, like this:
convert input.png -channel red -fx "1" -channel green -fx "1" -channel blue -fx "1" output.jpg

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