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Allow separate parameters for gamma encoding and decoding (#1439)

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Daiz
2018-11-11 11:15:38 +02:00
committed by Lovell Fuller
parent 1fa388370e
commit a48f8fbb61
8 changed files with 41 additions and 5 deletions
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13
lib/operation.js
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@@ -189,12 +189,13 @@ function flatten (options) {
* then increasing the encoding (brighten) post-resize at a factor of `gamma`.
* This can improve the perceived brightness of a resized image in non-linear colour spaces.
* JPEG and WebP input images will not take advantage of the shrink-on-load performance optimisation
* when applying a gamma correction.
* when applying a gamma correction. Supply a second argument to use a different output gamma value, otherwise the first value is used in both cases.
* @param {Number} [gamma=2.2] value between 1.0 and 3.0.
* @param {Number} [gammaOut] value between 1.0 and 3.0. Defaults to same as gamma.
* @returns {Sharp}
* @throws {Error} Invalid parameters
*/
function gamma (gamma) {
function gamma (gamma, gammaOut) {
if (!is.defined(gamma)) {
// Default gamma correction of 2.2 (sRGB)
this.options.gamma = 2.2;
@@ -203,6 +204,14 @@ function gamma (gamma) {
} else {
throw new Error('Invalid gamma correction (1.0 to 3.0) ' + gamma);
}
if (!is.defined(gammaOut)) {
// Default gamma correction for output is same as input
this.options.gammaOut = this.options.gamma;
} else if (is.number(gammaOut) && is.inRange(gammaOut, 1, 3)) {
this.options.gammaOut = gammaOut;
} else {
throw new Error('Invalid post gamma correction (1.0 to 3.0) ' + gammaOut);
}
return this;
}