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Add extractChannel operation to extract a channel from an image (#497)

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This commit is contained in:
Matt Hirsch
2016-07-09 11:48:30 -04:00
committed by Lovell Fuller
parent f672f86b53
commit 83d8847f57
8 changed files with 119 additions and 0 deletions
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10
src/pipeline.cc
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@@ -789,6 +789,15 @@ class PipelineWorker : public AsyncWorker {
image = Bandbool(image, baton->bandBoolOp);
}
// Extract an image channel (aka vips band)
if(baton->extractChannel > -1) {
if(baton->extractChannel >= image.bands()) {
(baton->err).append("Cannot extract channel from image. Too few channels in image.");
return Error();
}
image = image.extract_band(baton->extractChannel);
}
// Override EXIF Orientation tag
if (baton->withMetadata && baton->withMetadataOrientation != -1) {
SetExifOrientation(image, baton->withMetadataOrientation);
@@ -1175,6 +1184,7 @@ NAN_METHOD(pipeline) {
baton->extendBottom = attrAs<int32_t>(options, "extendBottom");
baton->extendLeft = attrAs<int32_t>(options, "extendLeft");
baton->extendRight = attrAs<int32_t>(options, "extendRight");
baton->extractChannel = attrAs<int32_t>(options, "extractChannel");
// Output options
baton->progressive = attrAs<bool>(options, "progressive");
baton->quality = attrAs<int32_t>(options, "quality");

2
src/pipeline.h
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@@ -94,6 +94,7 @@ struct PipelineBaton {
double convKernelScale;
double convKernelOffset;
VipsOperationBoolean bandBoolOp;
int extractChannel;
int tileSize;
int tileOverlap;
VipsForeignDzContainer tileContainer;
@@ -155,6 +156,7 @@ struct PipelineBaton {
convKernelScale(0.0),
convKernelOffset(0.0),
bandBoolOp(VIPS_OPERATION_BOOLEAN_LAST),
extractChannel(-1),
tileSize(256),
tileOverlap(0),
tileContainer(VIPS_FOREIGN_DZ_CONTAINER_FS),