The LqrCarver objects are initialised from a plain buffer representing an image. The default constructor assumes a colour depth of 8 bits per channel:

Here, buffer is the array representing an image of size width by height with channels colour channels per pixels. Thus, the overall buffer size has to be of widht * height * channels unsigned characters, and ordered such that the k-th colour of the pixel at row y and column x is found at:

buffer[(y * width + x) * channels + k]

(this assumes that x, y and k all start from 0 and reach the maximum values widht-1, height-1 and channels-1, respectively)

The function returns a pointer to the newly allocated LqrCarver upon success, or NULL in case of insufficient memory.

In order to create LqrCarver objects with more than 8 bits per channel, an extended version of the constructor must be used:

The differnece with the default version is that the input buffer must be passed as void, and its type must be specified through the additional parameter colour_depth, which can take one of the following values:

Floating point type values must range between 0 and 1.

The library has some support for different image types and color models. When a LqrCarver object is created, the image type is automatically set from the number of channels (basically, assuming that the image is either grayscale or RGB with possibly an alpha channel), but it is important to set it manually using the function lqr_carver_set_image_type if your program has to deal with different color models. See the section Choosing the image type for more details.

By default, the buffer is assumed to be a copy of the original image, and therefore it is owned by the LqrCarver object and must not be accessed directly any more (and of course it must not be freed, the LqrCarver destructor does it). If, instead, you want the Liquid Rescale library to keep the buffer intact, you must flag the LqrCarver after creation (or after activation), using this function:

This function must be used before any other operation takes place.

The newly created LqrCarver consists only of the image buffer plus an uninitialised visibility map. If one had a previously computed visibility map, it could be imported into the LqrCarver and that would be enough (see the Importing a visibility map in a carver section).

If the visibility map has to be computed, the LqrCarver needs to be initialised through this function:

Here, delta_x is the maximum allowed transversal step of the seams (0 means straight seams, the typical value is 1), while the rigidity parameter can be used to introduce a global bias for non-straight seams (the typical value is 0; a nonzero value can be modulated locally for specific areas using the functions described in section Adding a rigidity mask).

The library supports a small number of different image types/color models in order to correctly compute quantities such as the brightness of a pixel, which are important for automatic feature detection.

The image type can be set manually using the function:

The type LqrImageType is an enum which can take these values:

When creating a LqrCarver object, the image type is inferred from the number of channels according to this table:

When setting a carver to LQR_CUSTOM_IMAGE, it is assumed that there are no alpha or black channels, but if there are, their index can be specified with the functions:

Use the value -1 in the indices arguments to unset those channels. Note that using LQR_CUSTOM_IMAGE in a carver normally requires special care in the choice and definitions of the energy functions (see the Automatic feature detection section).