Synopsis:

#include <imp.h>

void impPackRow(uchar_t *dptr, short *sptr, int n);
void impUnpackRow(short *dptr, uchar_t *sptr, int n);

impPackRow() converts the array of short integers pointed to by sptr into the array of unsigned char values pointed to by dptr. Source data that is too large to fit in a character is truncated. For example, the source value 0x0B56 is converted into 0x56 in the destination array. impUnpackRow() converts the array of unsigned char values pointed to by sptr into the array of short integers pointed to by dptr. For example, the source value 0x56 is converted into 0x0056 in the destination array. The parameter n specifies the number of elements in the source and destination arrays.

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Note: The allocation of storage for the source and destination arrays is the responsibility of the caller.

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See also:

libimp(3)

Synopsis:

#include <imp.h>

void impPerror(const char *str);
char* impErrorString(int errCode);
extern int IMPerrno;

impPerror() prints error messages to standard error in a format similar to the standard C library function perror(3C). If an error occurs during a libimp function call, the global error variable IMPerrno is set with an error code. The error code is either a system error code (errno) or a libimp-specific code. The symbolic names for the libimp error codes are defined in imp.h. The value of IMPerrno is used by impPerror() as an index to a table of error messages.

impPerror() prints user-supplied string str followed by a colon (:), a space, and the error message corresponding to the current value of IMPerrno.

If the string str is the NULL string (""), no colon or space is printed, only the error message. The error message is either a system error message or a libimp-specific message. To be of most use, a call to impPerror should be made immediately following the libimp function call where an error has been detected. impErrorString() is similar to the strerror(3C) function and returns the error message corresponding to the error code specified by errCode.

If errCode is less than IMP_ERR_BASE, the message returned is a system error message generated by strerror. If errCode is one of the error codes specified in imp.h, the returned string is a libimp-specific error message.

See also:

libimp(3), perror(3C), strerror(3C)

Synopsis:

#include <imp.h>

int impReadRow(IMPImage *image, short *buffer,
   ushort_t row, ushort_t channel);
int impReadRowB(IMPImage *image, uchar_t *buffer,
   ushort_t row, ushort_t channel);

int impWriteRow(IMPImage *image, short *buffer,
   ushort_t row, ushort_t channel);
int impWriteRowB(IMPImage *image, uchar_t *buffer,
   ushort_t row, ushort_t channel);

impReadRow() and impReadRowB() each read a row of image data from the specified channel of a Silicon Graphics image format file.

impReadRow() stores the row data in an array of short integers and can read image data that is one or two bytes per pixel per channel in width. impReadRowB() stores the data in a character array and can handle only image data that is one byte per pixel per channel wide.

If impReadRowB() is called to read image data that is two bytes per pixel per channel, an error condition is reported. impWriteRow() and impWriteRowB() each write a row of image data to the specified channel of a Silicon Graphics image file. impWriteRow() writes one or two bytes per pixel per channel image row data. impWriteRowB() writes only one byte per pixel data. It is an error to use impWriteRowB() to write to images that expect two bytes per pixel per channel data.

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Note: The functions make use of the following macros:

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The functions take the following parameters:

Return Value:

If execution was successful, all functions return the number of pixels (not bytes) read or written. If an execution error occurred, -1 is returned and IMPerrno is set.

Execution Error Codes:

impWriteRow() and impWriteRowB() fail with the following errors:

impReadRow() and impReadRowB() fail with the following errors:

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Note: It is the caller's responsibility to allocate enough buffer storage for image row data.

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See also:

libimp(3), impOpen(3)

Figure B-1 shows the equation for W conversions.

Figure B-1. W Conversions

Synopsis:

#include <imp.h>

void impRGBtoW(short *rbuf, short *gbuf, short *bbuf,
   short *wbuf, int n);

void impWtoRGB(short *wbuf, short *rbuf, short *gbuf,
    short *bbuf, int n);

Figure B-2 shows the equation for K conversions.

Figure B-2. K Conversions

Synopsis:

#include <imp.h>

void impRGBtoK(short *rbuf, short *gbuf, short *bbuf,
   short *kbuf, short unity, int n);

void impKtoRGB(short *kbuf, short *rbuf, short *gbuf,
    short *bbuf, short unity, int n);

Figure B-3 shows the equation for CMY conversions.

Figure B-3. CMY Conversions

Synopsis:

#include <imp.h>

void impRGBtoCMY(short *rbuf, short *gbuf, short *bbuf,
   short *cbuf, short *mbuf, short *ybuf,
   short unity, int n);

void impCMYtoRGB(short *cbuf, short *mbuf, short *ybuf,
   short *rbuf, short *gbuf, short *bbuf,
   short unity, int n);

Figure B-4 shows the equation for YIQ conversions.

Figure B-4. YIQ Conversions

Synopsis:

#include <imp.h>

void impRGBtoYIQ(short *rbuf, short *gbuf, short *bbuf,
   short *ybuf, short *ibuf, short *qbuf,
   int n);

void impYIQtoRGB(short *ybuf, short *ibuf, short *qbuf,
   short *rbuf, short *gbuf, short *bbuf,
   int n);

Figure B-5 shows the equation for YUV conversions.

Figure B-5. YUV Conversions

Synopsis:

#include <imp.h>

void impRGBtoYUV(short *rbuf, short *gbuf, short *bbuf,
   short *ybuf, short *ubuf, short *vbuf,
   int n);

void impYUVtoRGB(short *ybuf, short *ubuf, short *vbuf,
   short *rbuf, short *gbuf, short *bbuf,
   int n);

Figure B-6 shows the equation for YCbCr conversions.

Figure B-6. YCbCr Conversions

Synopsis:

#include <imp.h>

void impRGBtoYCbCr(short *rbuf, short *gbuf, short *bbuf,
   short *ybuf, short *cbbuf, short *crbuf, int n);

void impYCbCrtoRGB(short *ybuf, short *cbbuf, short *crbuf,
   short *rbuf, short *gbuf, short *bbuf, int n);

Figure B-7 shows the equation for CMYK conversions.

Figure B-7. CMYK Conversions

Synopsis:

#include <imp.h>

void impRGBtoCMYK(short *rbuf, short *gbuf, short *bbuf,
   short *cbuf, short *mbuf, short *ybug,
   short *kbuf, short unity, int n);

void impRGBtoDevCMYK(short *rbuf, short *gbuf, short *bbuf,
   short *cbuf, short *mbuf, short *ybug,
   short *kbuf, IMPUCRFunc ucr, IMPBGFunc bg,
   short unity, int n);

short (*IMPBGFunc)(short k);
short (*IMPUCRFunc)(short k);

void impCMYKtoRGB(short *cbuf, short *mbuf, short *ybuf,
   short *kbuf, short *rbuf, short *gbug,
   short *bbuf, short unity, int n);

Synopsis:

#include <imp.h>

void impRGBtoHSV(short *rbuf, short *gbuf, short *bbuf,
   float *hbuf, float *sbuf, float *vbuf, int n);

void impHSVtoRGB(float *hbuf, float *sbuf, float *vbuf,
   short *rbuf, short *gbuf, short *bbuf, int n);

For HSV conversions, refer to Computer Graphics, Principals and Practice, Foley and Van Dam, 2nd Edition, pages 590-592. For HLS conversions, refer to pages 592-595.

Synopsis:

#include <imp.h>

void impRGBtoHLS(short *rbuf, short *gbuf, short *bbuf,
   float *hbuf, float *lbuf, float *sbuf,
   short unity, int n);

void impHLStoRGB(float *hbuf, float *lbuf, float *sbuf,
   short *rbuf, short *gbuf, short *bbuf,
   short unity, int n);

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Note: It is the caller's responsibility to allocate all buffer storage.

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See also:

libimp(3)

Synopsis:

#include <imp.h>

void impZeroRow(short *dptr, int n);

void impInitRow(short *dptr, int val, int n);

void impCopyRow(short *dptr, short *sptr, int n);

void impSAddRow(short *dptr, short *sptr, int val, int n);

void impVAddRow(short *dptr, short *sptr1, short *sptr2, int n);

void impSSubRow(short *dptr, short *sptr, int val, int n);

void impVSubRow(short *dptr, short *sptr1, short *sptr2, int n);

void impSMulRow(short *dptr, short *sptr, int val, int n);

void impSDivRow(short *dptr, short *sptr, int val, int n);

void impClampRow(short *dptr, short *sptr, int lov, int hiv, int n);

In the following descriptions, the parameter n specifies the number of elements in an array and not the number of bytes in the array. In addition, functions that take a source array pointer and a destination array pointer can specify the same array as both a source and destination.

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Note: It is the caller's responsibility to allocate all buffer storage. Also, because the arrays referenced by these functions are short integer arrays, the caller should be aware of overflow/wraparound conditions.

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See also:

libimp(3)

Synopsis:

#include <imp.h>

IMPZoom* impCreateZoom(ushort_t srcXSize, ushort_t srcYSize,
   ushort_t dstXSize, ushort_t dstYSize,
   IMPReadRowFunc readRowFunc,
   int numChannels,
   IMPFilterType filterType,
   float blurFactor);

void impDestroyZoom(IMPZoom *zoom);

void impResetZoom(IMPZoom *zoom);

int impZoomRow(IMPZoom *zoom, short *buffer,
   ushort_t row, void *clientData);

The libimp library provides an API for performing image resizing or zooming. Images can be zoomed up or down using any of a number of resampling methods. The resampling methods divide into two categories. The first resampling category is non-filtered zooming (also known as replicative zoom, decimation). The second resampling category is filtered zooming where a filter of a given shape is applied to the data. The image zooming is performed on a row-by-row basis using a one-pass, two-dimensional convolution.

To zoom one or more rows of an image, first create a zoom operator by calling impCreateZoom(). One of the parameters to impCreateZoom() is a pointer to a function that is called during the zoom to read rows of the source image. To obtain zoomed rows, call impZoomRow(). When all desired zoomed rows have been obtained, call impDestroyZoom() to deallocate storage held by the zoom operator. When filtered zooming is performed, a number of contiguous rows of image data are cached. Often all rows of a given image channel are zoomed, followed by all rows of the next channel. Since rows are cached, the cache should be flushed when switching between image channels. The impResetZoom() function performs this row cache flushing operation.

The impCreateZoom() function has the following parameters:

int (*IMPReadRowFunc)(short *buffer,
   ushort_t row,
   void *clientData);

The function should read the image row indicated by row and place the data in buffer. The storage for buffer is allocated and deallocated by the zoom operator and should not be manipulated by the read row function. clientData is a pointer to caller-specific information. The caller may specify a pointer to client data when calling the impZoomRow() function. That pointer is passed to the read row function.

At the caller's discretion, this pointer may be set to NULL. A common use of the client data is to pass a pointer to a structure containing the image structure pointer and the channel number. The read row function must return -1 if it encounters an error while obtaining the row data and must return a value of 0 or greater if the function succeeds.

The impZoomRow() function has the following parameters:

The resampling filters available for zooming are summarized below. Note that the span of the filter (x range) is expressed in terms of the original image, not the zoomed image. Table B-3 lists the available filter functions.

Return Value:

The impCreateZoom() function returns a pointer to a zoom operator structure if execution was successful. NULL is returned and IMPerrno is set if an execution error has occurred.

The impZoomRow() function returns 0 if execution was successful. -1 is returned and IMPerrno is set if an execution error occurred.

Execution Error Codes:

The impCreateZoom() function fails with the following error:

The impZoomRow() function fails with the following error:

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Note: The storage for the IMPZoom structure is allocated by the zoom operator creation function. This storage is deallocated by the impDestroyZoom() function. The caller should not explicitly reallocate or deallocate any storage related to the image structure. Furthermore, the fields of the IMPZoom structure are private and should not be modified by the caller.

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See also:

libimp(3)