Using shell commands, I can perform the following on a PNG file that has transparency:
convert image.png -background Black -flatten image.png
And the resulting image now has a black background. How do I do this with the Magick++ API? I have an Image object that I'm using already for some other manipulation:
Image img(filename);
img.resize(Magick::Geometry("x48"));
img.unsharpmask(5.0, 0.5, 50.0, 50.0);
img.gamma(0.5);
...
Before I do the resizing, I need to take care of the image transparency and make it black instead.
Thanks.
The -flatten option can be found in STL.h and is called flattenImages. This method requires a container of images. Below is an example of how you can use the method.
Image img(filename);
Geometry size(img.columns(), img.rows());
Color color(0,0,0);
Image black(size, color);
std::list<Image> images;
images.push_back(black);
images.push_back(img);
Image flattenedImage;
flattenImages(&flattenedImage, images.begin(), images.end());
flattenedImage.resize(Geometry("x48"));
Related
I would like to blur only a part of an image. The part to blur is always rectangular, so that I can easily use the following command:
magick source.jpg -region 1000x1000+0+500 -blur 0x20 result.jpg
This works, but is pretty slow for large images. Since I have to process thousands of files again and again, this will simply take too long.
Therefore, I decided to do the blurring by downscaling and upscaling the image back to the original size. However, since this will blur the full image, I have tried to accomplish the task using the following steps:
take the original image as background
create a copy of the original image
blur the copy using down-/upscaling
crop the desired region from the blurred copy
compose the original and the blurred&cropped copy
I am already pretty close (I hope), but when composing the two images, the cropped image will always be positioned in the top-left corner of the original image - instead of the original position from the source image. This is my current command:
magick source.jpg ( -clone 0 -resize 5% -resize 2000% -crop 1000x1000+0+1000 ) -composite result.jpg
I have read in the documentation that the original canvas size will be retained when using the -crop operation, and that this size and position will be used when using -composite. However, this doesn't seem to work in my case. Does anyone have an idea why?
I have tried to use -repage, -extent and other options to define the size and position of the cropped image, but to no avail so far.
I would try -flatten in your command as that is used for layers.
You can do it with a mask image (of any shape) in ImageMagick. Though I am not sure if that will be faster than your scaling method.
Input:
Mask:
(note: blurring occurs where mask is black)
magick lena.jpg -write-mask mask.png -blur 0x3 +write-mask lena_blurred.png
Result:
I'm uploading base64 encoded image to a RoR application. When I receive the image, it has a rgb color scheme (correct), when I write the image on file to be uploaded with paperclip gem, the image color scheme change from rgb to grayscale.
Here is the code:
source = src.gsub(/^data:image\/(png|jpg|jpeg);base64,/,"")
blob = Base64.decode64(source)
img = Magick::Image.from_blob(blob).first
img.colorspace = Magick::SRGBColorspace
img.add_profile "#{Rails.root.to_s}/lib/color_profiles/RGB.icc"
img.write(url = "#{Rails.root.to_s}/tmp/#{self.id}_logo.png")
image = File.open(url)
the img is correctly a RGB image, if I check the resulted created file:
identify -format "%[colorspace]" #{url}
the color scheme is Gray.
Additional info:
The uploaded image is all black with white text, if I upload same image with red background, the final image is correctly an RGB image.
There seems to be a bug in ImageMagick 6.9.9.27 and 7.0.7.15 when reporting the conversion of a grayscale image to RGB PNG. Identify -verbose is reporting grayscale but the string format %[colorspace] is properly reporting sRGB as are the PNG tags. I have reported this bug. For example:
convert logo: -colorspace gray logo.jpg
convert logo.jpg PNG24:logo.png
convert logo.png -format "%[colorspace]" info:
sRGB
identify -verbose logo.png
...
Colorspace: Gray
...
png:IHDR.color-type-orig: 2
png:IHDR.color_type: 2 (Truecolor)
I do not understand. Is your image a color image or a grayscale only image?
IM 6.7.7.10 was during a time that ImageMagick was changing from non-linear gray to linear gray and back again. And also had RGB and sRGB swapped. So you may have a version where gray was linear (darker than non-linear gray) or where RGB and sRGB were swapped. You can convert back to non-linear using one of the following (I do not recall which to use at this time). The other will convert from linear to non-linear. If I assume your input image was grayscale and not color, then try one of these:
convert input -colorspace RGB -colorspace gray result
or
convert input -colorspace sRGB -colorspace gray result
If it is not grayscale, but color only, then leave off the -colorspace gray in these commands.
I would urge you to upgrade if you can. You are well over 200 versions old.
P.S. It is also possible your profile is causing a problem. I don't know what the RGB.icc profile is. Is that an Adobe RGB profile or an sRGB profile.
Can you reproduce your problem using Command Line ImageMagick? If so, post the command line you used. Sorry I do not know Ruby or RMagick.
P.S. 2 Apart from the lighter/darker issue, if you are trying to convert a grayscale image to color, then you will need to specify the output as PNG24:name.png. That is the only way to force a grayscale image to report colorspace=RGB without inserting color pixels.
I have a png image.
How can I cut a small rect from this image using imagemagick? (make a transparent hole in image)
For example:
Source:
Destination:
It seems I figure it out.
convert u1.png -alpha set -region 40x30+15+5 -alpha transparent u3.png
It cuts a rect (40x30) from u1.png
I have an animated GIF which is color, I would like to make it grayscale. How can I do this with ImageMagick? I've tried using this:
convert image.gif -fx "(r+g+b)/3" imageGS.gif
But this leaves me with a grayscale image that is just the first frame of the animation.
How do I tell ImageMagick to affect all the frames of the animation?
Use the modulate command instead and set the saturation to 0:
convert image.gif -modulate 100,0,100 imageGS.gif
I tested this with my own animated gif and it worked.
I'd like to use the ImageMagick convert tool to automatically generate a toolbar bitmap from several png images.
I'm using the following command line:
convert.exe -resize 32x32 #imagelist32.txt +append BMP3:toolbarlarge.bmp
with imagelist32.txt containing a list of png files (each one being one toolbar button).
This works, but the resulting bitmap uses black for the transparent color and white as the background color. I would need both colors to be RGB(192,192,192). Like if there was already an image with that background color, and the png images would be drawn on that background.
How can I do that? I've tried adding the -background #C0C0C0 and -transparent-color #C0C0C0 parameters but it didn't work - maybe I put them in the wrong order?
I know you've probably resolved it by your own, but I've been playing a bit with converter.exe some time ago, so I hope this is what you were looking for.
Set the -alpha parameter to the background flag, what means that every fully transparent pixel will be set to the background color, while leaving it fully transparent.
And set also the -background to a certain color RGB(192,192,192), so the previously transparent pixels will get this color.
convert.exe -resize 32x32 -alpha background -background RGB(192,192,192) #imagelist32.txt +append BMP3:toolbarlarge.bmp