Caire

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

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 github.com/esimov/caire/cmd/caire
$ go install

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
blur	1	Blur radius
sobel	10	Sobel filter threshold
debug	false	Use debugger

In case you wish to reduce the image size by a specific percentage, it can be used the -perc boolean flag, which means you need only to specify that you want to deal with percentages instead of concrete values. In this case the values provided for width and height will be expressed as percentage. Here is a sample command using -perc:

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

which reduces the image width & height by 20%.

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

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

Sample images

Shrinked images

Original	Shrinked

Enlarged images

Original	Extended

Useful resources

• https://en.wikipedia.org/wiki/Seam_carving
• https://inst.eecs.berkeley.edu/~cs194-26/fa16/hw/proj4-seamcarving/imret.pdf
• http://pages.cs.wisc.edu/~moayad/cs766/download_files/alnammi_cs_766_final_report.pdf
• https://stacks.stanford.edu/file/druid:my512gb2187/Zargham_Nassirpour_Content_aware_image_resizing.pdf

License

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