1. An image processing apparatus comprising:
an image input section into which an image is input;
a primary differential value calculating section which calculates a primary differential value of luminance on a peripheral area of a target pixel as any one pixel on the input image;
a secondary differential value calculating section which calculates a secondary differential value with respect to the primary differential value; and
a detecting section which detects a feature point based on the primary differential value and the secondary differential value.
2. The image processing apparatus according to claim 1, wherein the primary differential value calculating section calculates largeness and a direction of the primary differential value.
3. The image processing apparatus according to claim 2, wherein the secondary differential value calculating section calculates the secondary differential value in a direction perpendicular to the primary differential value.
4. The image processing apparatus according to claim 2, wherein the detecting section determines a direction of the feature point based on the primary differential value.
5. The image processing apparatus according to claim 1, wherein the detecting section detects a pixel whose both primary differential value and secondary differential value become large as the feature point.
6. The image processing apparatus according to claim 5, wherein the detecting section detects a corner portion present on the image as the feature point.
7. The image processing apparatus according to claim 1, wherein the detecting section determines presencenon-presence of the feature point based on a ratio between the primary differential value and the secondary differential value of the luminance on the peripheral area of the target pixel.
8. An image processing method for detecting a feature point on an image, comprising the steps of:
calculating a primary differential value of luminance on a peripheral area of a target pixel as any one pixel on the image;
calculating a secondary differential value with respect to the primary differential value; and
detecting the feature point based on the primary differential value and the secondary differential value.
9. A computer program for operating a computer as an image processing apparatus capable of detecting a feature point on an image, comprising:
a primary differential value calculating unit which calculates a primary differential value of luminance on a peripheral area of a target pixel as any one pixel on the image;
a secondary differential value calculating unit which calculates a secondary differential value with respect to the primary differential value; and
a detecting unit which detects the feature point based on the primary differential value and the secondary differential value.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An electro-optic Mach-Zehnder modulator, comprising
a first optical waveguide forming a first arm of the Mach-Zehnder modulator;
a second optical waveguide forming a second arm of the Mach-Zehnder modulator, wherein
the first andor the second optical waveguide comprises a plurality of capacitive segments spaced apart from one another, the capacitive segments each forming an electrical capacitor; and
a travelling wave electrode arrangement for applying a voltage across the first andor the second optical waveguide, the travelling wave electrode arrangement comprising
a plurality of waveguide electrodes arranged on the capacitive segments;
at least one electrical line extending at least partially along a part of the first andor the second optical waveguide, the electrical line being arranged in a distance from the waveguide electrodes; and
a plurality of connecting arrangements, wherein a connecting arrangement is assigned to each of the waveguide electrodes, where-in the connecting arrangements each comprise at least two connecting structures spaced apart from one another wherein the waveguide electrodes each are electrically connected to the electrical line via the assigned two connecting structures.
2. The Mach-Zehnder modulator as claimed in claim 1, wherein the at least two connecting structures are formed as contact bridges.
3. The Mach-Zehnder modulator as claimed in claim 1, wherein at least one connecting arrangement comprises at least two connecting structures that extend perpendicular to the first andor the second optical waveguide.
4. The Mach-Zehnder modulator as claimed in claim 1, wherein the electrical line is arranged coplanar to the waveguide electrodes.
5-10. (canceled)
11. The Mach-Zehnder modulator as claimed in claim 1, wherein one of the connecting structures is connected to a first end of the waveguide electrode and the other one of the two connecting structures is connected to the second end of the waveguide electrode.
12. The Mach-Zehnder modulator as claimed in claim 1, wherein the distance between the two connecting structures is at least half of the length\u2014measured along the first andor the second optical waveguide\u2014of the assigned waveguide electrode or at least two thirds of the length of the assigned waveguide electrode.
13. The Mach-Zehnder modulator as claimed in claim 1, wherein the width\u2014measured perpendicular to the first andor second optical waveguide\u2014of the electrical line is chosen in such a way that the impedance of the travelling wave electrode arrangement in a pre-determined frequency range neither exceeds a pre-determined maximum nor drops below a pre-determined minimum.
14. The Mach-Zehnder modulator as claimed in claim 1 formed as a semi-conductor device.
15. The Mach-Zehnder modulator as claimed in claim 1, wherein the capacitive segments comprise at least one p-doped layer.
16. The Mach-Zehnder modulator as claimed in claim 15, wherein the p-doped layer is removed between adjacent capacitive segments such that passive waveguide segments are formed.
17. The Mach-Zehnder modulator as claimed in claim 1, wherein the capacitive segments each form a p-i-n diode, an n-i-n diode or a Schottky diode.
18. Method of fabricating an electro-optic Mach-Zehnder modulator as claimed in claim 1, comprising the steps of
providing a first optical waveguide forming a first arm of the Mach-Zehnder modulator;
providing a second optical waveguide forming a second arm of the Mach-Zehnder modulator;
forming a plurality of capacitive segments of the first andor the second optical waveguide, the capacitive segments being spaced apart from one another and each forming an electrical capacitor; and
providing a travelling wave electrode arrangement for applying a voltage across the first andor the second optical waveguide, comprising
arranging a plurality of waveguide electrodes on the capacitive segments;
forming at least one electrical line extending along at least a part of the first andor the second optical waveguide, the electrical line being arranged in a distance from the waveguide electrodes,
forming at least two connecting structures for each one of the waveguide electrodes in such a way that the waveguide electrodes (211, 212) are electrically connected to the electrical line via the at least two connecting structures.
19. An electro-optic Mach-Zehnder modulator, comprising
a first optical waveguide forming a first arm of the Mach-Zehnder modula-tor;
a second optical waveguide forming a second arm of the Mach-Zehnder modulator (1), wherein
the first andor the second optical waveguide comprises a plurality of ca-pacitive segments spaced apart from one another, the capacitive segments each forming an electrical capacitor; and
a travelling wave electrode arrangement for applying a voltage across the first andor the second optical waveguide, the travelling wave electrode arrangement comprising
a plurality of waveguide electrodes arranged on the capacitive seg-ments
at least one electrical line extending at least partially along a part of the first andor the second optical waveguide, the electrical line being arranged in a distance from the waveguide electrodes; and
a plurality of connecting arrangements, wherein a connecting ar-rangement is assigned to each of the waveguide electrodes, the connecting arrangements each comprise a single wide connecting structure having a width that equals the length of the assigned waveguide electrode, wherein the width of the wide connecting structure and the length of the waveguide electrode are measured along the first andor the second optical waveguide, and wherein the waveguide electrodes each are electrically connected to the electrical line via the assigned single wide connecting structure, wherein the plurality of wide connecting structures is formed by a continuous contact struc-ture extending along the first andor the second optical waveguide, wherein the wide connecting structures are formed by portions of the continuous contact structure.
20. The Mach-Zehnder modulator as claimed in claim 19, wherein the capacitive seg-ments comprise at least one p-doped layer, wherein the p-doped layer is removed between adjacent capacitive segments such that passive waveguide segments are formed, and wherein the continuous contact structure extends over both the capacitive segments and the passive waveguide segments.
21. Method of fabricating an electro-optic Mach-Zehnder modulator as claimed in claim 19, comprising the steps of
providing a first optical waveguide forming a first arm of the Mach-Zehnder modulator;
providing a second optical waveguide forming a second arm of the Mach-Zehnder modulator;
forming a plurality of capacitive segments of the first andor the second optical waveguide, the capacitive segments being spaced apart from one another and each forming an electrical capacitor; and
providing a travelling wave electrode arrangement for applying a voltage across the first andor the second optical waveguide, comprising
arranging a plurality of waveguide electrodes on the capacitive seg-ments;
forming at least one electrical line extending along at least a part of the first andor the second optical waveguide, the electrical line being arranged in a distance from the waveguide electrodes,
forming a single wide connecting structure for each one of the wave-guide electrodes in such a way that the waveguide electrodes are electrically connected to the electrical line via the single wide connecting structure, respectively, wherein the width of the wide connecting structure is chosen to equal the length of the assigned waveguide electrode, the width of the wide connecting structure and the length of the waveguide electrode being measured along the first andor the second optical waveguide, wherein the plurality of wide connecting structures is formed by forming a continuous contact structure extending along the first andor the second optical waveguide in such a way that the wide connecting structures are formed by portions of the continuous contact structure.