imagemerge

gim - Grid Based Image Merge Library

gim is a image merging library that can accept image paths as input, read the image contents, add background color, draw layers on top of each other, merge them into a grid with the desired size.

Table of Contents

• Overview
• Installation
• Getting Started
• Examples
  • Grid Unit Count - Vertical & Horizontal
  • Grid Background Color
  • Grid Layers - Draw Grids on top of Grids
  • Filters
• Functional Options
• TODO

Overview

gim provides an easy and extensible way to merge images into a flexible grid system.

The main purpose of the library is to help creating image collages programmatically.

Installation

go get -u github.com/766b/go-image-merge

Getting Started

Import the library and give the image paths and grid size as the minimum required arguments.

Basic usage:

import gim "github.com/766b/go-image-merge"

// accepts *Grid instances, grid unit count x, grid unit count y
// returns an *image.RGBA object
grids := []*gim.Grid{
	{ImageFilePath: "file.jpg"},
	{ImageFilePath: "file.png"},
}
rgba, err := gim.New(grids, 2, 1).Merge()

// save the output to jpg or png
file, err := os.Create("file/path.jpg|png")
err = jpeg.Encode(file, rgba, &jpeg.Options{Quality: 80})
err = png.Encode(file, rgba)

See Examples for available options and advanced usage.

Examples

Grid Unit Count - Vertical & Horizontal

grids := []*gim.Grid{
    {ImageFilePath: "./cmd/gim/input/kitten.jpg"},
    {ImageFilePath: "./cmd/gim/input/kitten.jpg"},
    {ImageFilePath: "./cmd/gim/input/kitten.jpg"},
    {ImageFilePath: "./cmd/gim/input/kitten.jpg"},
}
rgba, err := gim.New(grids, 2, 2).Merge()

Output:

Grid Background Color

grids := []*gim.Grid{
    {
        ImageFilePath: "./cmd/gim/input/ginger.png",
        BackgroundColor: color.White,
    },
    {
        ImageFilePath: "./cmd/gim/input/ginger.png",
        BackgroundColor: color.RGBA{R: 0x8b, G: 0xd0, B: 0xc6},
    },
}
rgba, err := gim.New(grids, 2, 1).Merge()

Output:

Grid Layers - Draw Grids on top of Grids

grids := []*gim.Grid{
    {
        ImageFilePath: "./cmd/gim/input/ginger.png",
        BackgroundColor: color.White,
        // these grids will be drawn on top of the first grid
        Grids: []*gim.Grid{
            {
            	ImageFilePath: "./cmd/gim/input/tick.png",
            	OffsetX: 50, OffsetY: 20,
            },
        },
    },
    {
        ImageFilePath: "./cmd/gim/input/ginger.png",
        BackgroundColor: color.RGBA{R: 0x8b, G: 0xd0, B: 0xc6},
        // these grids will be drawn on top of the second grid
        Grids: []*gim.Grid{
            {
            	ImageFilePath: "./cmd/gim/input/tick.png",
            	OffsetX: 200, OffsetY: 170,
            },
            {
            	ImageFilePath: "./cmd/gim/input/tick.png",
            	OffsetX: 200, OffsetY: 20,
            },
        },
    },
}
rgba, err := gim.New(grids, 2, 1).Merge()

Output:

Filters

Available Filters

• Black & White: Converts an image to grayscale.
• Sepia: Applies a sepia filter to an image.
• Vignette: Applies a vignette filter to an image.

Applying Filters

To apply filters, include them in the Filters slice of the Grid struct. Each Grid can have multiple filters applied, which will be processed in the order they are added.

Example: Black & White Filter

grids := []*gim.Grid{
    {
        ImageFilePath:   "./cmd/gim/input/ginger2.png",
        Filters: []imagefilter.FilterType{
            imagefilter.BlackAndWhite,
        },
    },
    {
        ImageFilePath:   "./cmd/gim/input/ginger2.png",
    },
}

Output:

Functional Options

OptBaseDir

// you can omit the full path if you set a base dir
grids := []*gim.Grid{
    {ImageFilePath: "kitten.jpg"},
    {ImageFilePath: "kitten.jpg"},
}
rgba, err := gim.New(
	grids, 1, 2,
	gim.OptBaseDir("./cmd/gim/input"),
).Merge()

OptGridSize

// you can resize the grids in pixels
grids := []*gim.Grid{
    {ImageFilePath: "kitten.jpg"},
    {ImageFilePath: "kitten.jpg"},
}
rgba, err := gim.New(
	grids, 2, 1,
	gim.OptBaseDir("./cmd/gim"),
	gim.OptGridSize(200,150),
).Merge()

Output:

TODO

• Add colored background support
• Add resize support (stretch, fit etc.)
• Add filters