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J. Mando
J. Mando

Reputation: 405

Converting PDF/SVG to PNG with antialias off using Magick++

I've tried to convert a SVG file to PNG with antialiasing off in Magick++ but I wasn't successful. But I was able to convert the SVG file to PDF with another program and the use the ImageMagick convert command to convert the PDF file to PNG. How can I use ImageMagick to do it? The command I use for converting PDF to PNG is this:

convert +antialias -interpolate Nearest -filter point -resize 1000x1000 "img.pdf" PNG24:"filter.png"

Is there any way to use Magick++ to do that or better, convert SVG to PNG directly with antialiasing off?

Thanks in advance.

Edit:

The answer given in this post doesn't work for me. Possible because I'm using a colored SVG instead of 1-bit alpha channel. Also I mentioned in my question that I'm also looking for a way to do this in Magick++.

Upvotes: 1

Views: 1716

Answers (1)

emcconville
emcconville

Reputation: 24419

Magick++ has the Magick::Image::textAntiAlias & Magick::Image::strokeAntiAlias methods available, but they would only be useful if your parsing the SVG and rebuilding the image (i.e. roll-your-own SVG engine) one SVG element at a time.

As @ccprog pointed out in the comments; once the decoder utility rasters the vectors, the damage is done & setting the flags would not have an effect on the resulting resize.

Without seeing the SVG, I can only speculate what the problem is. I would suggest setting the document size before reading the SVG content.

For example, read the image at a smaller size than resample up.

Magick::Image img;
img.size(Magick::Geometry(100, 100)); // Decode to a small context
img.read("input.svg");
img.interpolate(Magick::NearestInterpolatePixel);
img.filterType(Magick::PointFilter);
img.resize(Magick::Geometry(600, 600));
img.write("PNG24:[email protected]");

output @ 100x100

Or render at larger size then the finial image.

Magick::Image img;
img.size(Magick::Geometry(1000, 1000)); // Decode to a larger context
img.read("input.svg");
img.interpolate(Magick::NearestInterpolatePixel);
img.filterType(Magick::PointFilter);
img.resize(Magick::Geometry(600, 600));
img.write("PNG24:[email protected]");

output @ 1000x1000

Update from comments

For Postscript (PDF) & True-Type antialiasing, you would set Magick::Image::textAntiAlias (or Magick::Image::antiAlias if using IM6) to false. Just ensure that the density is set to allow any overhead.

Magick::Image img;
img.density(Magick::Point(300));
if (MagickLibVersion < 0x700) {
    img.antiAlias(false);
} else {
    img.textAntiAlias(false);
}
img.interpolate(Magick::NearestInterpolatePixel);
img.filterType(Magick::PointFilter);
img.read("input.pdf");
img.resize(Magick::Geometry(1000, 1000));
img.write("PNG24:output.png");

Upvotes: 3

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