ImageGear for C and C++ on Windows v19.1 - Updated
Region of Interest Processing
User Guide > How to Work with... > Image Processing and Cleanup > Region of Interest Processing

This group of functions allows you to apply image processing and special effects functions on an arbitrary region of interest (ROI). You can specify a shape, such as ellipse, polygon, or freehand, or a 1-bit mask for identifying which pixels to include/exclude from image processing algorithms.

To apply an image processing function on a non-rectangular ROI, create the ROI using IG_IP_NR_ROI_to_HIGEAR_mask(), or use a 1-bit image, and associate it with the HIGEAR handle on which you are going to apply the processing function, using IG_IP_NR_ROI_mask_associate(). Consequent calls to image processing functions on this image will only affect the area specified by the ROI.

IG_IP_NR_ROI_control_get() Returns the current ROI control settings.
IG_IP_NR_ROI_control_set() Detects an area of pixels using a specified threshold.
IG_IP_NR_ROI_mask_associate() Associates a mask HIGEAR, as specified by the AT_NR_ROI_MASK structure, with the image referenced by hIGear.
IG_IP_NR_ROI_mask_delete() Deletes the mask HIGEAR created by IG_IP_NR_ROI_to_HIGEAR_mask().
IG_IP_NR_ROI_mask_dilate() Dilates ROI mask by the specified number of pixels.
IG_IP_NR_ROI_mask_erode() Erodes ROI mask by the specified number of pixels.
IG_IP_NR_ROI_mask_unassociate() Removes the non-rectangular ROI information from a HIGEAR image, but does not delete the mask HIGEAR.
IG_IP_NR_ROI_to_HIGEAR_mask() Builds a non-rectangular ROI mask from a set of segment descriptors that you pass in.