Sakurai/pdf.js
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Fixing interpolation (continuation of #1143)

Browse Source
This commit is contained in:
notmasteryet 2012-01-31 20:19:44 -06:00
parent 59283bdf6d
commit 5fba376a33
1 changed files with 49 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

66
src/function.js
View File

@ -156,33 +156,65 @@ var PDFFunction = (function PDFFunctionClosure() {
args.length);
var x = args;
var y = new Float64Array(n * m);
// Building the cube vertices: its part and sample index
// http://rjwagner49.com/Mathematics/Interpolation.pdf
var cubeVertices = 1 << m;
var cubeN = new Float64Array(cubeVertices);
var cubeVertex = new Uint32Array(cubeVertices);
for (var j = 0; j < cubeVertices; j++)
cubeN[j] = 1;
var k = n, pos = 1;
// Map x_i to y_j for 0 <= i < m using the sampled function.
for (var i = 0; i < m; ++i) {
// x_i' = min(max(x_i, Domain_2i), Domain_2i+1)
var domain_2i = domain[2 * i];
var domain_2i_1 = domain[2 * i + 1];
var domain_2i = domain[i][0];
var domain_2i_1 = domain[i][1];
var xi = Math.min(Math.max(x[i], domain_2i), domain_2i_1);
// e_i = Interpolate(x_i', Domain_2i, Domain_2i+1, Encode_2i, Encode_2i+1)
var e = interpolate(xi, domain_2i, domain_2i_1, encode[2 * i], encode[2 * i + 1]);
// e_i = Interpolate(x_i', Domain_2i, Domain_2i+1,
// Encode_2i, Encode_2i+1)
var e = interpolate(xi, domain_2i, domain_2i_1,
encode[i][0], encode[i][1]);
// e_i' = min(max(e_i, 0), Size_i - 1)
e = Math.min(Math.max(e, 0), size[i] - 1);
var size_i = size[i];
e = Math.min(Math.max(e, 0), size_i - 1);
var in = i * n;
for (var j = 0; j < n; ++j) {
// average the two nearest neighbors in the sampling table
var rj = (samples[Math.floor(e) * n + j] + samples[Math.ceil(e) * n + j]) / 2;
// r_j' = Interpolate(r_j, 0, 2^BitsPerSample - 1, Decode_2j, Decode_2j+1)
rj = interpolate(rj, 0, mask, 1, decode[2 * j], decode[2 * j + 1]);
// y_j = min(max(r_j, range_2j, range_2j+1)
y[in + j] = Math.min(Math.max(rj, range[2 * j], range[2 * j + 1]));
// Adjusting the cube: N and vertex sample index
var e0 = e < size_i - 1 ? Math.floor(e) : e - 1; // e1 = e0 + 1;
var n0 = e0 + 1 - e; // (e1 - e) / (e1 - e0);
var n1 = e - e0; // (e - e0) / (e1 - e0);
var offset0 = e0 * k;
var offset1 = offset0 + k; // e1 * k
for (var j = 0; j < cubeVertices; j++) {
if (j & pos) {
cubeN[j] *= n1;
cubeVertex[j] += offset1;
} else {
cubeN[j] *= n0;
cubeVertex[j] += offset0;
}
}
k *= size_i;
pos <<= 1;
}
var y = new Float64Array(n);
for (var j = 0; j < n; ++j) {
// Sum all cube vertices' samples portions
var rj = 0;
for (var i = 0; i < cubeVertices; i++)
rj += samples[cubeVertex[i] + j] * cubeN[i];
// r_j' = Interpolate(r_j, 0, 2^BitsPerSample - 1,
// Decode_2j, Decode_2j+1)
rj = interpolate(rj, 0, 1, decode[j][0], decode[j][1]);
// y_j = min(max(r_j, range_2j), range_2j+1)
y[j] = Math.min(Math.max(rj, range[j][0]), range[j][1]);
}
return y;