Image processing apparatus, method, and program for adding shadow information to images

An image processing apparatus, comprising:

• luminous intensity information separating means for separating input image information from an input image into global luminous intensity information and local luminous intensity information;
• band separating means for generating a plurality of local, per-band luminous intensity information by band-separating the local luminous intensity information;
• shadow component generating means for generating a shadow component of the image on the basis of the plurality of local, per-band luminous intensity information;
• control signal generating means for generating, on the basis of the input image information, a shadow addition control signal for controlling portions where the shadow component is to be suppressed;
• and
• image compositing means for generating output image information by adding shadow image information to the input image information, with the shadow image information being generated from the shadow component, from a value based on the input image information, and from the shadow addition control signal;
• normal vector computing means for computing a luminous intensity gradient of the local luminous intensity information as a normal vector with respect to an object surface in the input image,
• light vector computing means for computing, on the basis of the local luminous intensity information, a light vector that indicates the direction of a light source, and
• normalized inner product processing means for computing the shadow component on the basis of the normalized inner product between the normal vector and the light vector.

An image processing method implemented on at least one processor, the method comprising the steps of:

• separating input image information from an input image into global luminous intensity information and local luminous intensity information;
• computing a luminous intensity gradient of the local luminous intensity information as a normal vector with respect to an object surface in the input image;
• computing, on the basis of the local luminous intensity information, a light vector that indicates the direction of a light source;
• computing a shadow component on the basis of the normalized inner product between the normal vector and the light vector;
• and
• generating output image information by adding shadow image information to the input image information, with the shadow image information being generated from the shadow component and from a value based on the input image information.

A nontransitory computer-readable medium storing a program that causes a computer to execute the steps of:

• separating input image information from an input image into global luminous intensity information and local luminous intensity information;
• computing a luminous intensity gradient of the local luminous intensity information as a normal vector with respect to an object surface in the input image;
• computing, on the basis of the local luminous intensity information, a light vector that indicates the direction of a light source;
• computing a shadow component on the basis of the normalized inner product between the normal vector and the light vector;
• and
• generating output image information by adding shadow image information to the input image information, with the shadow image information being generated from the shadow component and from a value based on the input image information.

An image processing apparatus, comprising:

• a luminous intensity information separator configured to separate input image information from an input image into global luminous intensity information and local luminous intensity information;
• a shadow component generator configured to generate a shadow component of the image on the basis of the local luminous intensity information;
• and
• an image compositor configured to generate output image information by adding shadow image information to the input image information, with the shadow image, information being generated from the shadow component and from a value based on the input image information;
• a normal vector computer configured to compute a luminous intensity gradient of the local luminous intensity information as a normal vector with respect to an object surface in the input image,
• a light vector computer configured to compute, on the basis of the local luminous intensity information, a light vector that indicates the direction of a light source, and
• a normalized inner product processor configured to compute the shadow component on the basis of the normalized inner product between the normal vector and the light vector.

An image processing apparatus, comprising:

• a luminous intensity information separator configured to separate input image information from an input image into global luminous intensity information and local luminous intensity information;
• a band separator configured to generate a plurality of local, per-band luminous intensity information by band-separating the local luminous intensity information;
• a shadow component generator configured to generate a shadow component of the image on the basis of the plurality of local, per-band luminous intensity information;
• a control signal generator configured to generate, on the basis of the input image information, a shadow addition control signal for controlling portions where the shadow component is to be suppressed;
• an image compositor configured to generate output image information by adding shadow image information to the input image information, with the shadow image information being generated from the shadow component, from a value based on the input image information, and from the shadow addition control signal;
• a normal vector computer configured to compute a luminous intensity gradient of the local luminous intensity information as a normal vector with respect to an object surface in the input image,
• a light vector computer configured to compute, on the basis of the local luminous intensity information, a light vector that indicates the direction of a light source, and
• a normalized inner product processor configured to compute the shadow component on the basis of the normalized inner product between the normal vector and the light vector.