Tap Geometry Glossary
The tap geometry is a Euresys proprietary taxonomy that describes, with a standardized name, the geometrical properties characterizing the different taps of a multi-tap camera.
Taxonomy
The tap geometry is built by the concatenation of two composite fields:
<X-Geometry>_<Y-Geometry>
<X-Geometry > and <Y-Geometry > composite fields
The <X-Geometry> composite field describes the geometrical organization of the taps along the X-direction (image row). It is composed as follows:
<X-Regions>X(<X-Taps>)(<X-Ext>)
The <Y-Geometry> composite field describes the geometrical organization of the taps along the Y-direction (image column). It is composed as follows:
<Y-Regions>Y(<Y-Taps>)(<Y-Ext>)
<X-Regions> and <Y-Regions> mandatory fields
The <X-Regions> field declares the number of regions encountered across the X-direction.
Values range: 1 to 10.
The <Y-Regions> field declares the number of regions encountered across the Y-direction .
Values range: 2 to 3. The field is omitted when <Y-Regions> = 1.
<X-Taps> and <Y-Taps> optional fields
The <X-Taps> field declares the number of consecutive pixels along the X-direction that are extracted simultaneously in each region.
Values range: 2 to 10. The field is omitted when <X-Taps> = 1.
The <Y-Taps> field declares the number of consecutive pixels along the Y-direction that are extracted simultaneously in each region.
Values range: 2 to 3. The field is omitted when <Y-Taps> = 1.
<X-Ext> optional field
The <X-Ext> field declares the relative location of the pixels extractors across one row of the image.
Possibles values:
| Pixel extractors location | <X-EXT> value |
|---|---|
| At both ends of the image row | E |
| At the middle of the image row | M |
| At the right of each region | R |
| At the left of each region | ∅ |
| NOTE: | The <X-Ext> field is omitted when all pixel extractors are at the left of each region. |
<Y-Ext> optional field
The <Y-Ext> field declares the relative location of the pixels extractors across one column of the image.
Possibles values:
| Pixel extractors location | <X-EXT> value |
|---|---|
| At both ends of the image column | E |
| At the top of each region | ∅ |
| NOTE: | The <Y-Ext> field is omitted when all pixel extractors are at the top of each region. |
Examples of tap geometries
1X_1Y designates the tap geometry of a single-tap camera having 1 region across the X-direction and 1 region across the Y direction.
The pixels are delivered one at a time on a single tap beginning with the leftmost pixel of the top row, scanning progressively all the rows of the image one by one, and ending with the rightmost pixel of the bottom row.
1X2_1Y designates the tap geometry of a two-tap camera having 1 region across the X-direction and 1 region across the Y direction.
The pixels are delivered two at a time on two taps beginning with the two leftmost pixels of the top row, scanning progressively all the rows of the image one by one, and ending with the two rightmost pixels of the bottom row.
1X_1Y2 designates the tap geometry of a two-tap camera having 1 region across the X-direction and 1 region across the Y direction.
The pixels are delivered two at a time on two taps beginning with the two uppermost pixels of the first column , scanning progressively all the rows of the image two by two, and ending with the two lowermost pixels of the rightmost column.
2XE_2YE designates the tap geometry of a four-tap camera having 2 regions across the X-direction and 2 regions across the Y direction.
The pixels are delivered four at a time on four taps. Each region delivers its pixels on a single-tap using a specific scanning scheme:
| □ | The pixels of the upper left quadrant are delivered on tap 1 starting with the upper left pixel and ending with the lower right pixel of the region. |
| □ | The pixels of the upper right quadrant are delivered on tap 2 starting with the upper rightmost pixel and ending with the lower left pixel of the region. |
| □ | The pixels of the lower left quadrant are delivered on tap 3 starting with the lower left pixel and ending with the upper right pixel of the region. |
| □ | The pixels of the lower right quadrant are delivered on tap 4 starting with the lower rightmost pixel and ending with the upper left pixel of the region. |
Definitions
Tap
One pixel stream output port of the camera that delivers one pixel every clock cycle.
Adjacent taps
Two taps are adjacent when the extracted pixels are adjacent on the same row or on the same column.
X-Taps
Number of consecutive pixels along one region row that are extracted simultaneously.
Y-Taps
Number of consecutive pixels along one region column that are extracted simultaneously.
|
Two adjacent taps on the same row X-Taps=2; Y-Taps=1 |
Two adjacent taps on the same column X-Taps=1; Y-Taps=2 |
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Region
A rectangular area of adjacent pixels that are transferred in a raster-scan order through one or multiple adjacent taps.
X-Regions
Number of regions encountered across one image row (= the X-direction or the horizontal direction). Possible values are 1, 2, 3, 4, 6, 8, and 10.
Y-Regions
Number of regions encountered across vertical direction. Possible values are 1 and 2.
|
Two regions on the same row X-Regions=2; Y-Regions=1 |
Two regions on the same column X-Regions=1; Y-Regions=2 |
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Tap geometrical properties
| □ | X-Start: X-position of the first extracted pixel of a camera readout cycle |
| □ | X-End: X-position of the last extracted pixel of a camera readout cycle |
| □ | Y-Start: Y-position of the first extracted pixel of a camera readout cycle |
| □ | Y-End: Y-position of the last extracted pixel of a camera readout cycle |
| □ | Y-Step: the difference of Y-position between consecutive rows of pixels; it is positive when Y-position values are increasing (top to bottom); it is negative otherwise. |
| □ | X-Position: the pixel column number in the (non-flipped) image; column 1 is the leftmost column; column W is the rightmost column of an image having a width of W pixels. |
| □ | Y-Position: the pixel row number in the (non-flipped) image; row 1 is the topmost row; row H is the bottommost row of an image having a height of H pixels. |