I am in a situation where I have a set of images with variable width and height and I need to ensure that those images comply with an aspect ratio of 2:1.
The only assumption I can make is that those images have an aspect ratio greater than 2 so I need to expand the canvas.
With ImageMagick I can do this:
magick input.jpg -background black -gravity north -extent 2:1 output.jpg
But this crops instead of adding canvas as desired. Is there an option to avoid cropping, i.e. force image padding? Remember I do not know the image resolution beforehand.
Of course with a more complex script I can extract the image dimensions and compute the desired resolution but I am trying to keep things simple if possible.
P.S.: The images comes from a laser scanner and are going to be used in a 360 panorama viewer hence the need to meet an aspect ration without cropping.
With ImageMagick v7 you can do some inline calculations that will adjust the results of the -extent operation to pad any size input to a 2:1 ratio. See this command as an example...
magick input.png -gravity center -extent "%[fx:max(w,h*2)]x%[fx:max(w/2,h)]" result.png
That will pad any extra space with black. Add -background <somecolor> before the extent operation to change the padding color.
Related
I need to take an image and append a mirror image of itself to the right (or left). It's got to do with mapping surfaces around spheres where some surface maps do not have left and right sides that "match up". (Digression: Is there is a name for the characteristic of an image whose right and left sides can be placed next to each other, wrapped around a cylinder or sphere, seamlessly?). Appending a mirror image to itself is a quick and dirty way to fix this problem in an environment where the image is chaotic and the viewer won't notice the trick being played.
This ImageMagick command almost does the trick but the problem is, it extends the image vertically as well as horizontally but leaves the vertical extent as an empty transparency. I just want a horizontal, mirror image extension:
convert original.jpg -background transparent -extent 200% \( +clone -flop \) -composite mirror.jpg
I need the -extent option to only extend in the horizontal direction. The ImageMagick documentation doesn't cover percentage values for -extent, only ratios like -extent 4:3 or absolute dimensions like -extent 800x600 but -extent 200% isn't in the documentation. Something like -extent 200% right is what I want. I have many images to run this transformation on and do not want to manually enter dimensions.
I have an PNG with an alpha channel. First I want to find all elements in the png, then I want to stretch the last color on the border about 5 to 10 pixels out
The stretching has to be in all directions from the center of each object on the image (like triangle, rectangle...)
It is important that I keep the color of each pixel on the edge
Is this possible? Goal is in the future to automate the process with ImageMagick.
I have had a play with distort and it is probably the way to go but needs more investigation. I was working on a smaller image and the code is basically a proof of concept.
I think edge is the key option and with this example I reduced the size of the resized image all round by 20px in the distort.
I do not know how you would get the angled edges though.I know you do not want to distort the original but it may give you some ideas as to how to get the result you want.
convert "1.png" -trim -matte -virtual-pixel edge -mattecolor none -interpolate Spline +distort BilinearForward "0,0 20,20 400,0 380,20 400,95 380,55 0,95 20,55" -trim +repage "result.png"
I am not quite sure what is going on at the edges of your image, but this should get you started...
First, I trim off any transparent edges (with -trim) so we get to the actual pattern you seek to extend. Then clone the image and dispose of everything except the top row of pixels (with -crop). Then scale that row up till it is 800 pixels tall. Then exchange the tall top row with the original image in the processing order (using +swap) and append the original image below the height-extended top row.
convert cells.png -trim +repage \( +clone -crop x1+0+0 -scale x800! \) +swap -append result.png
I have portrait and landscape JPEG images.
I want to make square thumbnails with white background from all of them. I need to keep the aspect ratio of all images and reduce the larger border to 200px.
I want to use ImageMagick (CLI) but I don't know how to do that. Any idea ?
Here is the individual images :
I think you need this:
convert -background white -gravity center \
input.jpg -resize 200x200 -extent 200x200 result.jpg
I want to remove background unnecessary greyed pixels in above image.
May i know how to do that.
Quick and dirty with ImageMagick:
convert 9AWLa.png -blur x1 -threshold 50% out.png
Somewhat better, still with ImageMagick:
convert 9AWLa.png -morphology thicken '1x3>:1,0,1' out.png
Updated Answer
It is rather harder to keep the noisy border intact while removing noise elsewhere in the image. Is it acceptable to trim 3 pixels off all the way around the edge, then add a 3 pixel wide black border back on?
convert 9AWLa.png -morphology thicken '1x3>:1,0,1' \
-shave 3x3 -bordercolor black -border 3 out.png
Some methods that come to my mind are
If the backgroud is gray color rather than sparse black dots then you can convert the image in binary by thresholding it with proper value of grayscale. i.e. all values above particular values of pixel are white and all values below that are black. Something like this.
Another thing you can do is first smoothing the picture my some filter like mean or median filter and then converting into binary presented in previous point.
I think in this way the unnecessary background can be removed
I'm using graphicsmagick to resize an image to a thumbnail, but it's adding a white surrounding border padding.
The command I'm using is:
gm convert matrix.jpg -resize "80x80>" -gravity center -extent 80x80 thumbnail.jpeg
As you can see, there is some white padding around the image, but I don't want this. Ideally I'd like (the entire image not just a crop of it) to fill the desired 80x80 output size.
How can this be achieved in either imagemagick or graphicsmagick?
I used ImageMagick with this image. This solution requires to know the size of the input image.
Input
The image has 145 pixels horizontally and 200 pixels vertically.
Crop
Crop from the top of the image:
convert -crop 145x145+0+0 -resize 80x80 matrix.jpg thumbnail.jpeg
I used 145x145 in order to extract a square from the original image. +0+0 is the offset of the extracted square, hereby the top left.
Crop with the center of the image:
convert -crop 145x145+0+27 -resize 80x80 matrix.jpg thumbnail.jpeg
The vertical offset is set to 27 because we have to remove 55 (200 - 145) pixels on top or bottom, so we need to remove 27 (55 รท 2) pixels on the top and 28 pixels on the bottom.
Crop with the bottom of the image:
convert -crop 145x145+0+55 -resize 80x80 matrix.jpg thumbnail.jpeg
Resizing without crop
convert -resize 80x80\! matrix.jpg thumbnail.jpeg
The ! flag (escaped with \! as suggested in the documentation) after the resize parameters forces ImageMagick to ignore the aspect ratio.
If you want to keep the original aspect ratio, without image distortion, you can use the ImageMagick -trim option to get rid of the white padding:
convert "matrix.jpg" -resize "80x80" -gravity center -extent 80x80
-trim "thumbnail.jpg"
This will produce a 58x80 uncropped image with the same aspect ratio as the original. It is 58x80 because ImageMagick uses the larger dimension of the original to compute the scale factor (in this case 80/200) and scales the smaller dimension by that same factor to preserve aspect ratio.
If you want an uncropped image of exactly 80x80 pixels, this is a different aspect ratio than the original. The output image will have distortion, and #AL's resizing without crop option will work.
convert "matrix.jpg" -resize "80x80!" -gravity center -extent 80x80
"thumbnail.jpg"
Tested in Windows 7 with ImageMagick 6.8.9. #AL syntax is probably Linux.