ImageGear for C and C++ on Linux v20.0 - Updated
API Reference Guide > Core Component API Reference > Core Component Functions Reference > Image Processing Functions > IG_IP_arithmetic_rect

This function performs an arithmetic or logical operation on two images, allowing you to specify a rectangular region of the first image on which to perform the operation.


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AT_ERRCOUNT ACCUAPI IG_IP_arithmetic_rect(
   HIGEAR hIGear1,
   HIGEAR hIGear2,
   LPAT_RECT lpImageRect2,
   AT_MODE nOperation


Name Type Description
hIGear1 HIGEAR HIGEAR handle of image 1, which is also the destination image.
hIGear2 HIGEAR HIGEAR handle of image 2.
lpImageRect2 LPAT_RECT Specifies a rectangle in hIGear2, which will be used for processing. Set to NULL for the whole image.
nOperation AT_MODE Specifies the kind of arithmetic operation to perform on the images. See enumIGMergeModes for possible values.

Return Value:

Returns 0 if successful. Otherwise, returns the number of ImageGear errors that occurred during this function call.

Supported Raster Image Formats:

All pixel formats supported by ImageGear for C and C++.


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HIGEAR hIGear1;            // HIGEAR handle of the first image
HIGEAR hIGear2;            // HIGEAR handle of the second image
AT_DIMENSION nWidth, nHeight;  // Dimensions of the first image
AT_ERRCOUNT nErrcount;    // Count of errs on stack upon ret from func
AT_RECT rcRect;            // Region to merge

// Load image file "picture.bmp" from working directory
nErrcount = IG_load_file("picture.bmp", &hIGear1);
if(nErrcount == 0)
    nErrcount = IG_load_file("picture.tif", &hIGear2);
    if(nErrcount == 0)
        // Get dimensions of the first image and initialize merging region
        IG_image_dimensions_get(hIGear1, &nWidth, &nHeight, NULL);
        rcRect.left = 0; = 0;
        rcRect.right = nWidth / 2;
        rcRect.bottom = nHeight / 2;

        nErrcount = IG_IP_arithmetic_rect(hIGear1, hIGear2, &rcRect, IG_ARITH_ADD);
        // ...
        // Destroy the second image
    // Destroy the first image


This function, like other ImageGear Image Processing and Clipboard API calls, takes an AT_RECT structure as an argument, so that you can merge a rectangular sub-region of hIGear2 into hIGear1. However, before ImageGear performs the operation specified by this function, it will check to see if an internal NRA flag has been set to TRUE, indicating that a mask HIGEAR should be used with the image. If the flag is set to TRUE, and a valid pointer to a mask image has been assigned, ImageGear will override the settings passed to the AT_RECT structure and use the non-rectangular ROI defined by the mask HIGEAR. To create a non-rectangular region of interest, call IG_IP_NR_ROI_to_HIGEAR_mask.

IG_IP_merge is an extended version of IG_IP_arithmetic_rect that allows specifying a rectangular area on the first image to be used for processing, as well as the coordinates in the first image where to place the upper-left corner of the specified rectangle of the second image.

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