-
-
Notifications
You must be signed in to change notification settings - Fork 1.3k
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
Add normalize() for simple histogram stretching
Available as normalize() or normalise(). Normalization takes place in LAB place and thus should not change any colors. Existing alpha channels are preserved untouched by normalization.
- Loading branch information
Showing
9 changed files
with
240 additions
and
3 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Loading
Sorry, something went wrong. Reload?
Sorry, we cannot display this file.
Sorry, this file is invalid so it cannot be displayed.
Loading
Sorry, something went wrong. Reload?
Sorry, we cannot display this file.
Sorry, this file is invalid so it cannot be displayed.
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Loading
Sorry, something went wrong. Reload?
Sorry, we cannot display this file.
Sorry, this file is invalid so it cannot be displayed.
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,136 @@ | ||
'use strict'; | ||
|
||
var assert = require('assert'); | ||
|
||
var sharp = require('../../index'); | ||
var fixtures = require('../fixtures'); | ||
|
||
sharp.cache(0); | ||
|
||
describe('Normalization', function () { | ||
|
||
it('uses the same prototype for both spellings', function () { | ||
assert.strictEqual(sharp.prototype.normalize, sharp.prototype.normalise); | ||
}); | ||
|
||
it('spreads rgb image values between 0 and 255', function(done) { | ||
sharp(fixtures.inputJpgWithLowContrast) | ||
.normalize() | ||
.raw() | ||
.toBuffer(function (err, data, info) { | ||
if (err) throw err; | ||
var min = 255, max = 0, i; | ||
for (i = 0; i < data.length; i += 3) { | ||
min = Math.min(min, data[i], data[i + 1], data[i + 2]); | ||
max = Math.max(max, data[i], data[i + 1], data[i + 2]); | ||
} | ||
assert.strictEqual(0, min); | ||
assert.strictEqual(255, max); | ||
return done(); | ||
}); | ||
}); | ||
|
||
it('spreads grayscaled image values between 0 and 255', function(done) { | ||
sharp(fixtures.inputJpgWithLowContrast) | ||
.gamma() | ||
.greyscale() | ||
.normalize() | ||
.raw() | ||
.toBuffer(function (err, data, info) { | ||
if (err) throw err; | ||
var min = 255, max = 0, i; | ||
for (i = 0; i < data.length; i++) { | ||
min = Math.min(min, data[i]); | ||
max = Math.max(max, data[i]); | ||
} | ||
assert.strictEqual(0, min); | ||
assert.strictEqual(255, max); | ||
return done(); | ||
}); | ||
}); | ||
|
||
it('stretches greyscale images with alpha channel', function (done) { | ||
sharp(fixtures.inputPngWithGreyAlpha) | ||
.normalize() | ||
.raw() | ||
.toBuffer(function (err, data, info) { | ||
// raw toBuffer does not return the alpha channel (yet?) | ||
var min = 255, max = 0, i; | ||
for (i = 0; i < data.length; i++) { | ||
min = Math.min(min, data[i]); | ||
max = Math.max(max, data[i]); | ||
} | ||
assert.strictEqual(0, min); | ||
assert.strictEqual(255, max); | ||
return done(); | ||
}); | ||
}); | ||
|
||
it('keeps an existing alpha channel', function (done) { | ||
sharp(fixtures.inputPngWithTransparency) | ||
.normalize() | ||
.toBuffer(function (err, data, info) { | ||
sharp(data) | ||
.metadata() | ||
.then(function (metadata) { | ||
assert.strictEqual(4, metadata.channels); | ||
assert.strictEqual(true, metadata.hasAlpha); | ||
assert.strictEqual('srgb', metadata.space); | ||
}) | ||
.finally(done); | ||
}); | ||
}); | ||
|
||
it('keeps the alpha channel of greyscale images intact', function (done) { | ||
sharp(fixtures.inputPngWithGreyAlpha) | ||
.normalize() | ||
.toBuffer(function (err, data, info) { | ||
sharp(data) | ||
.metadata() | ||
.then(function (metadata) { | ||
assert.strictEqual(true, metadata.hasAlpha); | ||
// because of complications with greyscale | ||
// we return everything in srgb for now. | ||
// | ||
// assert.strictEqual(2, metadata.channels); | ||
// assert.strictEqual('b-w', metadata.space); | ||
assert.strictEqual(4, metadata.channels); | ||
assert.strictEqual('srgb', metadata.space); | ||
}) | ||
.finally(done); | ||
}); | ||
}); | ||
|
||
it('returns a black image for images with only one color', function (done) { | ||
sharp(fixtures.inputPngWithOneColor) | ||
.normalize() | ||
.toBuffer() | ||
.bind({}) | ||
.then(function (imageData) { | ||
this.imageData = imageData; | ||
return sharp(imageData) | ||
.metadata(); | ||
}) | ||
.then(function (metadata) { | ||
assert.strictEqual(false, metadata.hasAlpha); | ||
// because of complications with greyscale | ||
// we return everything in srgb for now. | ||
// | ||
// assert.strictEqual(1, metadata.channels); | ||
// assert.strictEqual('b-w', metadata.space); | ||
assert.strictEqual(3, metadata.channels); | ||
assert.strictEqual('srgb', metadata.space); | ||
}) | ||
.then(function () { | ||
return sharp(this.imageData) | ||
.raw() | ||
.toBuffer(); | ||
}) | ||
.then(function (rawData) { | ||
// var blackBuffer = new Buffer([0,0,0,0]); | ||
var blackBuffer = new Buffer([0,0,0, 0,0,0, 0,0,0, 0,0,0]); | ||
assert.strictEqual(blackBuffer.toString(), rawData.toString()); | ||
}) | ||
.finally(done); | ||
}); | ||
}); |