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README.md

Caire

Build Status license release homebrew

Caire is a content aware image resize library based on Seam Carving for Content-Aware Image Resizing paper.

How does it work

  • An energy map (edge detection) is generated from the provided image.
  • The algorithm tries to find the least important parts of the image taking into account the lowest energy values.
  • Using a dynamic programming approach the algorithm will generate individual seams accrossing the image from top to down, or from left to right (depending on the horizontal or vertical resizing) and will allocate for each seam a custom value, the least important pixels having the lowest energy cost and the most important ones having the highest cost.
  • Traverse the image from the second row to the last row and compute the cumulative minimum energy for all possible connected seams for each entry.
  • The minimum energy level is calculated by summing up the current pixel with the lowest value of the neighboring pixels from the previous row.
  • Traverse the image from top to bottom and compute the minimum energy level. For each pixel in a row we compute the energy of the current pixel plus the energy of one of the three possible pixels above it.
  • Find the lowest cost seam from the energy matrix starting from the last row and remove it.
  • Repeat the process.

The process illustrated:

Original image Energy map Seams applied
original sobel debug

Features

Key features which differentiates from the other existing open source solutions:

  • Customizable command line support
  • Support for both shrinking or enlarging the image
  • Resize image both vertically and horizontally
  • Can resize all the images from a directory
  • Does not require any third party library
  • Use of sobel threshold for fine tuning
  • Use of blur filter for increased edge detection

To Do

  • Face detection

Install

First, install Go, set your GOPATH, and make sure $GOPATH/bin is on your PATH.

$ export GOPATH="$HOME/go"
$ export PATH="$PATH:$GOPATH/bin"

Next download the project and build the binary file.

$ go get -u -f github.com/esimov/caire/cmd/caire
$ go install

MacOS (Brew) install

The library now can be installed via Homebrew. The only thing you need is to run the commands below.

$ brew tap esimov/caire
$ brew install caire

Usage

$ caire -in input.jpg -out output.jpg

Supported commands:

$ caire --help

The following flags are supported:

Flag Default Description
in n/a Input file
out n/a Output file
width n/a New width
height n/a New height
perc false Reduce image by percentage
square false Reduce image to square dimensions
blur 1 Blur radius
sobel 10 Sobel filter threshold
debug false Use debugger

In case you wish to scale down the image by a specific percentage, it can be used the -perc boolean flag. For example to reduce the image dimension by 20% both horizontally and vertically you can use the following command:

caire -in input/source.jpg -out ./out.jpg -perc=1 -width=20 -height=20 -debug=false

Also the library supports the -square option. When this option is used the image will be resized to a squre, based on the shortest edge.

The CLI command can process all the images from a specific directory too.

$ caire -in ./input-directory -out ./output-directory

Sample images

Shrunk images

Original Shrunk
broadway_tower_edit broadway_tower_edit
waterfall waterfall
dubai dubai
boat boat

Enlarged images

Original Extended
gasadalur gasadalur
dubai dubai

Useful resources

License

This project is under the MIT License. See the LICENSE file for the full license text.