2d.color.type.u8p3.to.f16srgb.to.u8p3.html

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This WPT test may be referenced by the following Test IDs:
- /html/canvas/offscreen/color-type/2d.color.type.u8p3.to.f16srgb.to.u8p3.html - WPT Dashboard Interop Dashboard

<!DOCTYPE html>

<!-- DO NOT EDIT! This test has been generated by /html/canvas/tools/gentest.py. -->

<meta charset="UTF-8">

<title>OffscreenCanvas test: 2d.color.type.u8p3.to.f16srgb.to.u8p3</title>

<script src="/resources/testharness.js"></script>

<script src="/resources/testharnessreport.js"></script>

<script src="/html/canvas/resources/canvas-tests.js"></script>

<h1>2d.color.type.u8p3.to.f16srgb.to.u8p3</h1>

<p class="desc">test srgb float16 canvas storing 8-bit display-p3 data accurately</p>

<script>

var t = async_test("test srgb float16 canvas storing 8-bit display-p3 data accurately");

var t_pass = t.done.bind(t);

var t_fail = t.step_func(function(reason) {

    throw reason;

});

t.step(function() {

  var canvas = new OffscreenCanvas(100, 50);

  var ctx = canvas.getContext('2d', {colorType: "float16", colorSpace: "srgb"});

  // Consider the color in Display P3:

  //   (5,250,128)/255

  // In sRGB this is:

  //   (-0.4990661502955996, 0.9982902153915844, 0.43901323244980783)

  // Quantized to float16, this is:

  //   (0xB7FC, 0x3BFC, 0x3706)

  //   (-0.49902344,         0.9980469,          0.43896484)

  // Converted back to Display P3 this is:

  //   (4.783888129523, 249.938708036787, 127.979725000698)/255

  // Quantized to 8-bit, this is:

  //   (5, 250, 128)

  var input = new ImageData(new Uint8ClampedArray([5, 250, 128, 255]),

                            1, 1, {colorSpace: "display-p3"});

  ctx.putImageData(input, 0, 0);

  var readback = ctx.getImageData(0, 0, 1, 1, {colorSpace:"display-p3"});

  const kEpsilon = 2;

  assert_approx_equals(readback.data[0], 5, kEpsilon);

  assert_approx_equals(readback.data[1], 250, kEpsilon);

  assert_approx_equals(readback.data[2], 128, kEpsilon);

  t.done();

});

</script>