tjtransform Struct Reference

Lossless transform. More...

#include <turbojpeg.h>

Data Fields
tjregion	r
	Cropping region.
int	op
	One of the transform operations.
int	options
	The bitwise OR of one of more of the transform options.
int(*	customFilter )(short *coeffs, tjregion arrayRegion, tjregion planeRegion, int componentIndex, int transformIndex)
	A callback function that can be used to modify the DCT coefficients after they are losslessly transformed but before they are transcoded to a new JPEG file.

---

Detailed Description

Lossless transform.

---

Field Documentation

int(* tjtransform::customFilter)(short *coeffs, tjregion arrayRegion, tjregion planeRegion, int componentIndex, int transformIndex)

A callback function that can be used to modify the DCT coefficients after they are losslessly transformed but before they are transcoded to a new JPEG file.

This allows for custom filters or other transformations to be applied in the frequency domain.

Parameters:

coeffs	pointer to an array of DCT coefficients. (NOTE: this pointer is not guaranteed to be valid once the callback returns, so applications wishing to hand off the DCT coefficients to another function or library should make a copy of them within the body of the callback.)
arrayRegion	region structure containing the width and height of the DCT coefficient array as well as its offset relative to the component plane. TurboJPEG implementations may choose to split each component plane into multiple DCT coefficient arrays and call the callback function once for each array.
planeRegion	region structure containing the width and height of the component plane to which this DCT coefficient array belongs
componentIndex	the component plane to which this DCT coefficient array belongs (Y, Cb, and Cr are, respectively, 0, 1, and 2 in typical JPEG images.)
transformIndex	the transformed image to which this DCT coefficient array belongs

Returns:

0 if the callback was successful, or -1 if an error occurred.

int tjtransform::op

One of the transform operations.

int tjtransform::options

The bitwise OR of one of more of the transform options.

tjregion tjtransform::r

Cropping region.

---

The documentation for this struct was generated from the following file:

• turbojpeg.h