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|
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
- Face detection
First, install Go, set your
GOPATH, and make sure
$GOPATH/bin is on your
$ 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
$ caire -in input.jpg -out output.jpg
$ caire --help
The following flags are supported:
||false||Reduce image by percentage|
||10||Sobel filter threshold|
In case you wish to reduce the image size by a specific percentage, it can be used the
-perc boolean flag, which means the image will be reduced to the width and height expressed as percentage. Here is a sample command using
caire -in input/source.jpg -out ./out.jpg -perc=1 -width 20 -height 20 -debug=false
which reduces the image width and height by 20%.
The CLI command can process all the images from a specific directory too.
$ caire -in ./input-directory -out ./output-directory
This project is under the MIT License. See the LICENSE file for the full license text.
- func Grayscale(src *image.NRGBA) *image.NRGBA
- func Resize(s SeamCarver, img *image.NRGBA) (image.Image, error)
- func SobelFilter(img *image.NRGBA, threshold float64) *image.NRGBA
- func Stackblur(img *image.NRGBA, width, height, radius uint32) *image.NRGBA
- type ActiveSeam
- type Carver
- func (c *Carver) AddSeam(img *image.NRGBA, seams Seam, debug bool) *image.NRGBA
- func (c *Carver) ComputeSeams(img *image.NRGBA, p *Processor) float64
- func (c *Carver) FindLowestEnergySeams() Seam
- func (c *Carver) RemoveSeam(img *image.NRGBA, seams Seam, debug bool) *image.NRGBA
- func (c *Carver) RotateImage270(src *image.NRGBA) *image.NRGBA
- func (c *Carver) RotateImage90(src *image.NRGBA) *image.NRGBA
- type Processor
- type Seam
- type SeamCarver
- type UsedSeams
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Implement the Resize method of the Carver interface.
func SobelFilter ¶
Detect image edges. See https://en.wikipedia.org/wiki/Sobel_operator
type ActiveSeam ¶
Struct containing the current seam color and position.
NewCarver returns an initialized Carver structure.
Add new seam.
func (*Carver) ComputeSeams ¶
Compute the minimum energy level based on the following logic:
- traverse the image from the second row to the last row and compute the cumulative minimum energy M for all possible connected seams for each entry (i, j). - the minimum energy level is calculated by summing up the current pixel value with the minimum pixel value of the neighboring pixels from the previous row.
func (*Carver) FindLowestEnergySeams ¶
Find the lowest vertical energy seam.
func (*Carver) RemoveSeam ¶
Remove the least important columns based on the stored energy seams level.
func (*Carver) RotateImage270 ¶
Rotate image by 270 degree counter clockwise
type SeamCarver ¶
SeamCarver is an interface that Carver uses to implement the Resize function. It takes an image and the output as parameters and returns the resized image.