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Merge pull request #9325 from Snuffleupagus/decodeACSuccessive-less-blur

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Adjust `decodeACSuccessive` in src/core/jpg.js to improve the rendering quality of (progressive) JPEG images
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Tim van der Meij 2017-12-30 19:26:07 +01:00 committed by GitHub
commit 4cc0f8c721
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GPG Key ID: 4AEE18F83AFDEB23
4 changed files with 52 additions and 42 deletions
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17
src/core/jpg.js
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@ -235,7 +235,8 @@ var JpegImage = (function JpegImageClosure() {
var s; var s;
var rs; var rs;
while (k <= e) { while (k <= e) {
var z = dctZigZag[k]; let offsetZ = offset + dctZigZag[k];
let sign = component.blockData[offsetZ] < 0 ? -1 : 1;
switch (successiveACState) { switch (successiveACState) {
case 0: // initial state case 0: // initial state
rs = decodeHuffman(component.huffmanTableAC); rs = decodeHuffman(component.huffmanTableAC);
@ -259,8 +260,8 @@ var JpegImage = (function JpegImageClosure() {
continue; continue;
case 1: // skipping r zero items case 1: // skipping r zero items
case 2: case 2:
if (component.blockData[offset + z]) { if (component.blockData[offsetZ]) {
component.blockData[offset + z] += (readBit() << successive); component.blockData[offsetZ] += sign * (readBit() << successive);
} else { } else {
r--; r--;
if (r === 0) { if (r === 0) {
@ -269,17 +270,17 @@ var JpegImage = (function JpegImageClosure() {
} }
break; break;
case 3: // set value for a zero item case 3: // set value for a zero item
if (component.blockData[offset + z]) { if (component.blockData[offsetZ]) {
component.blockData[offset + z] += (readBit() << successive); component.blockData[offsetZ] += sign * (readBit() << successive);
} else { } else {
component.blockData[offset + z] = component.blockData[offsetZ] =
successiveACNextValue << successive; successiveACNextValue << successive;
successiveACState = 0; successiveACState = 0;
} }
break; break;
case 4: // eob case 4: // eob
if (component.blockData[offset + z]) { if (component.blockData[offsetZ]) {
component.blockData[offset + z] += (readBit() << successive); component.blockData[offsetZ] += sign * (readBit() << successive);
} }
break; break;
} }

1
test/pdfs/.gitignore vendored
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@ -67,6 +67,7 @@
!issue9105_reduced.pdf !issue9105_reduced.pdf
!issue9291.pdf !issue9291.pdf
!bad-PageLabels.pdf !bad-PageLabels.pdf
!decodeACSuccessive.pdf
!filled-background.pdf !filled-background.pdf
!ArabicCIDTrueType.pdf !ArabicCIDTrueType.pdf
!ThuluthFeatures.pdf !ThuluthFeatures.pdf

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test/pdfs/decodeACSuccessive.pdf Normal file
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8
test/test_manifest.json
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@ -3589,6 +3589,14 @@
"type": "eq", "type": "eq",
"nativeImageDecoderSupport": "none" "nativeImageDecoderSupport": "none"
}, },
{ "id": "decodeACSuccessive",
"file": "pdfs/decodeACSuccessive.pdf",
"md5": "7749c032624fe27ab8e8d7d5e9a4a93f",
"rounds": 1,
"link": false,
"type": "eq",
"nativeImageDecoderSupport": "none"
},
{ "id": "issue5592", { "id": "issue5592",
"file": "pdfs/issue5592.pdf", "file": "pdfs/issue5592.pdf",
"md5": "a0750f95afa80c880f7966df7062616c", "md5": "a0750f95afa80c880f7966df7062616c",