EP0491036A1 - Circuit associant de maniere selective les signaux de coefficient de puissance de deux - Google Patents

Circuit associant de maniere selective les signaux de coefficient de puissance de deux

Info

Publication number
EP0491036A1
EP0491036A1 EP19910913760 EP91913760A EP0491036A1 EP 0491036 A1 EP0491036 A1 EP 0491036A1 EP 19910913760 EP19910913760 EP 19910913760 EP 91913760 A EP91913760 A EP 91913760A EP 0491036 A1 EP0491036 A1 EP 0491036A1
Authority
EP
European Patent Office
Prior art keywords
multiplexer
adder
multiplexers
input
registers
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP19910913760
Other languages
German (de)
English (en)
Inventor
Kenneth Alan Parulski
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Eastman Kodak Co
Original Assignee
Eastman Kodak Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Eastman Kodak Co filed Critical Eastman Kodak Co
Publication of EP0491036A1 publication Critical patent/EP0491036A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T3/00—Geometric image transformations in the plane of the image
    • G06T3/40—Scaling of whole images or parts thereof, e.g. expanding or contracting
    • G06T3/4007—Scaling of whole images or parts thereof, e.g. expanding or contracting based on interpolation, e.g. bilinear interpolation
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
    • G06F17/10—Complex mathematical operations
    • G06F17/17—Function evaluation by approximation methods, e.g. inter- or extrapolation, smoothing, least mean square method
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
    • G06F17/10—Complex mathematical operations
    • G06F17/17—Function evaluation by approximation methods, e.g. inter- or extrapolation, smoothing, least mean square method
    • G06F17/175—Function evaluation by approximation methods, e.g. inter- or extrapolation, smoothing, least mean square method of multidimensional data

Definitions

  • the present invention is directed to a circuit which selectably combines power of two coefficients for interpolation and filter control and, more particularly, to a circuit capable of producing a linear interpolation commonly used in digital signal processing of color signals where the invention reduces the integrated circuit chip area used by the interpolation circuit.
  • Linear interpolation circuits are commonly used in digital signal processing systems, and particularly in image processing systems.
  • the simplest form of linear interpolation is 1 to 2 interpolation.
  • an original image from a CCD camera might have 500 lines of pixels, while the printer or display may require 1,000 lines.
  • the simplest way to obtain a 1000 line image is to simply replicate each camera line twice when displaying or printing.
  • a preferred technique is to set the values of every second
  • SUBSTITUT output line equal to the values of the original lines from the camera, and to set the values of "interpolated" lines in between the original lines equal to the average of the values from the two vertically adjacent original lines from the camera.
  • This technique referred to as 1 to 2 linear interpolation, can be implemented in hardware very easily using an adder, a hardwired bit shift to divide by 2, and a multiplexer, as illustrated in Fig. 1.
  • the original pixel values from two adjacent original lines (line n and line n+1) from the camera are loaded into registers 10 and 12. Each register outputs 1/2 the original value by hardwired shifting.
  • the most significant nine bits are passed to the adder as the least significant bits of the 10 bit adder input and the most significant bit of the adder input is set to zero.
  • the two most significant bits of the next stage are set to zero and the eight most significant bits are supplied to the least significant bits of the next stage, if a 1/8 value is needed, the three most significant bits of the next stage are set to zero and only the seven most significant bits are supplied to the least significant bits of the next stage, and so on for other binary divisions.
  • the adder 14 stores the result of the addition in a register 16.
  • a multiplexer 18 then alternately stores either the original pixel values or the linearly interpolated values into an output register 20 depending on whether the output line number is even or odd. In this operation, the addition of the shifted original pixel values is performed before the multiplex operation.
  • a 1 to 4 linear interpolation is a common operation in many image processing applications. Two such circuits are used in a digital signal processor chip produced by Eastman Kodak Company as described in the U.S. Application previously mentioned.
  • the general operation of a 1 to 4 interpolation technique is illustrated in figure 2. For each original pixel 30 in the input image, the circuit computes four "output" pixel values. One of the output pixel values 30 equals the original pixel 30.
  • the other three output pixel values 32, 34 and 36 are linearly weighted combinations of the values of the nearest original pixels on the left and the right, if horizontal interpolation is being performed or top and bottom if vertical interpolation is being performed.
  • the weights are 3/4 times the left pixel plus 1/4 times the right pixel for the first produced pixel 32, 1/2 times the left pixel plus 1/2 times the right pixel for the second produced pixel 34, and 1/4 times the left plus 3/4 times the right for the third produced pixel 36.
  • Figure 3A shows one of the two identical "horizontal chroma interpolator" circuits shown as Fig. 7 of the application mentioned above.
  • the two "original" pixel values are loaded into the top two registers 40 and 42 every fourth master clock cycle (See Fig. 3B) .
  • a 4 to 1 multiplexer 44 which is actually composed of three 2 to 1 multiplexers, is used to set the output equal to one of four values (See Fig. 3C) .
  • CHR0MAPIX(2) * 00 the value in register 42 is used.
  • CHROMAPIX(2) 01
  • the output is set equal to 3/4 of the register 42 pixel value plus 1/4 of the register 40 pixel value.
  • FIG. 3A is the simplest prior art l to 4 interpolation circuit known and includes seven registers 40, 42, 46, 48, 50, 52 and 54, five adders 56, 58, 60, 62 and 64, and a 4 to 1 multiplexer or three 2 to 1 multiplexers. Another method of performing a linear interpolation is to use multipliers and interpolation coefficients stored in registers. This approach uses even more chip area than the approach discussed above.
  • an interpolation circuit that multiplexes inputs prior to one or more additions during the interpolation operation.
  • the multiplexers select among different divide shifted inputs and apply the shifted inputs to adders in a sequence that produces the desired binary based combined or interpolated values.
  • Fig. 1 illustrates a conventional 1 to 2 interpolation circuit,*
  • Fig. 2 illustrates a 1 to 4 interpolation operation
  • Fig. 3A depicts a conventional 1 to 4 interpolation circuit
  • Fig. 3B is a timing diagram of the control signals for the circuit of Fig. 3A;
  • Fig. 3C is a control signal state diagram showing the interpolation coefficients of the circuit of Fig. 3A;
  • Fig. 4 depicts a 1 to 2 interpolation or signal combining circuit in accordance with the present invention
  • Fig. 5A illustrates a 1 to 4 interpolation circuit in accordance with the present invention
  • Fig. 5B is a timing diagram of the control signals for the circuit of Fig. 5A;
  • Fig. 5C is a control signal state diagram showing the interpolation coefficients of the circuit of Fig. 5A;
  • Fig. 6A depicts a 1 to 8 interpolation circuit in accordance with the present invention
  • Fig. 6B is a state diagram of the control signals and interpolation coefficients for the circuit of Fig.6A;
  • Fig. 7A is a spline interpolation circuit in accordance with the present invention
  • Pig. 7B is a control signal state diagram for the circuit of Fig. 7A;
  • Fig. 8A illustrates a linear signal mixer in accordance with the present invention
  • Fig. 8B illustrates the control signal state diagram for the circuit of Fig. 8A.
  • the present invention is based on the observation that each adder shown in the circuit of Fig. 3A is used only once every four master clock cycles, even though the adders are designed to complete an operation every master clock cycle. Therefore, the adders are essentially sitting idle 75% of the time. Furthermore, at most two adders are required to compute any of the interpolated output values. One adder is needed to sum 1/2 and 1/4 of a first original pixel value and a second adder is needed " to sum this result with 1/4 of the second original pixel value.
  • the principle behind the present invention is to select different divide shifted signals using multiplexers before the addition operation is performed.
  • the key to the present invention is in determining how to properly multiplex the inputs to the adders.
  • the principle of the present invention is illustrated in Fig. 4 where two registers 80 and 82 feed a multiplexer 84 which selects one of the two registers.
  • multiplexer 84 selects register 80 and stores that value in register 86.
  • the contents of register 86 are shift divided by two and added to a shift divided output from register 82 and stored in register 90 producing the interpolated value.
  • multiplexer 84 selects the contents of register 82 and, as a result, register 90 receives the sum of 1/2 of the value in register 82 from multiplexer 84 and 1/2 of the value in register 82.
  • This circuit performs the multiplex operations prior to the addition operation, which is in contrast to the sequence illustrated in Fig. 1.
  • a comparison of Fig. 1 with Fig. 4 indicates that the number of circuit components for a one to two interpolation circuit in accordance with the present invention is the same as in the conventional circuit. However, the number of circuit components necessary in the present invention begins dropping with respect to the number of circuit components required in the conventional circuit, when the number of interpolated values increases, as illustrated in Fig. 5A.
  • a 1 to 4 interpolation circuit in accordance with the present invention shown in Fig. 5A requires only two adders, compared to five for the conventional circuit of Fig. 3A, and only five rather than six registers.
  • the circuit needs four, rather than three, 2 to 1 multiplexers, one OR gate, and one invertor. Since the adders require by far the most chip area, this new circuit takes less than one-half of the area of the conventional circuit of Fig. 3A. Yet the present invention takes the same amount of time to perform the interpolation as the conventional circuit.
  • the circuit of Fig. 5A operates using the same clocking signals required by the conventional circuit of Fig. 3A and is a drop-in replacement for the prior art circuit.
  • the original pixels are latched into the left and right registers 100 and 102 every four master clock (CK) cycles and four pixels are produced for every clock cycle of CK43.
  • the A and B multiplexers 104 and 106 determine whether the left or right inputs are routed to the A and B adder inputs.
  • the 0 and 1 values next to the inputs of the multiplexers indicate which input is selected based on the value of the select signal, for example, when select A is 1 the content of register 102 is selected and when select A is 0 the content of register 100 is selected.
  • select A is 1 the content of register 102 is selected and when select A is 0 the content of register 100 is selected.
  • adder B (118) outputs to output register 120 a value which equals 1/2 the value in the right register 102 plus 1/2 the value in the right register 102.
  • multiplexer A (104) selects the left register 100 while multiplexer B (106) selects the right register 102.
  • multiplexer C (108) selects the 1/4 input, so that the register C (112) value equals 3/4 left
  • Multiplexer D (114) selects the 1/4 input, so that the register D (116) value equals 1/4 right. This gives the proper output.
  • the multiplexer A (104) and multiplexer B (106) selection is simply reversed.
  • multiplexer A (104) selects right 102 while multiplexer B (106) selects left 100.
  • FIG. 5B illustrates the clock signals applied to the circuit of Fig. 5A to accomplish the above-described operation. However, as can be seen by comparing the timing signal diagrams of Fig. 3B with the corresponding diagrams in Fig. 5B, the phases of the chroroapix signals needs to be adjusted, a task within the ordinary skill in the art. By making such an adjustment the output arrives at the same phase relative to CK43 as in the conventional circuit. Fig.
  • FIG. 5C illustrates the translation of the two control signals chromapix 1 and chromapix 0 into the multiplexer selection signals A, B, C and D.
  • the present invention includes an invertor 122 along with an OR gate 124 which produces the select A signal from the control signals chromapix (2).
  • the remaining selection signals B, C and D are unmodified control signals.
  • the map illustrated in Fig. 5C also depicts the interpolation coefficients produced as a result of the particular state of the control signals where X is the location in the pixel stream of the produced pixel, for example, when chromapix (2) « 00 the pixel adjacent to the original right pixel is produced.
  • the present invention can be used to advantage any time a hardware implementation of a 1 to 4 interpolation is required.
  • the basis of the present invention is to count the minimum number of adders needed to obtain the roost adder intensive interpolated output value and then develop a circuit using this many adders along with multiplexers to appropriately provide the bit shifted or zero inputs to the adders.
  • This approach can be extended to any other size interpolation circuit.
  • a 1 to 3 interpolation circuit does not benefit from the present invention, since the 1/3 plus 2/3 terms are best implemented with multiplexers which have programmable coefficients instead of bit shifted additions.
  • a 1 to 6 or 1 to 8 interpolator benefits considerably from the present invention since these interpolators would normally be implemented with multipliers.
  • Fig. 6A illustrates how the present invention can be applied to a 1 to 8 interpolator.
  • a 1 to 8 interpolator circuit in accordance with the present invention also includes two registers 140 and 142, the contents of which are selected by multiplexers 144 and 146 in a first stage.
  • a set of second stage multiplexers 148, 150, 152 and 154 select from appropriately shifted outputs from the first stage multiplexers, or from zero values, and supply the selected values to adder 156 and adder/subtractor 158.
  • the second stage multiplexer 152 shows a "-1/8" input value. During actual operation only a 1/8 value is transferred through multiplexer 152 and the sign input to the adder/subtractor 158 is set to produce a negative input.
  • Adders 156 and 158 supply stage storage registers 160 and 162 which feed an adder 164 that produces the output stored in register 166.
  • the control signals, the resulting interpolation coefficients and the pixel being produced are illustrated in Fig. 6B. It is possible to produce the control signals using a logic circuit with appropriate AND, OR and inverter gates, however, with a complicated control signal set such as illustrated in Fig. 6B it would also be appropriate to provide these values from a memory storage device such as a ROM or a RAM which can be sequentially addressed by a counter incremented by a master clock signal. With the use of a programmable RAM to control the circuit of Fig. 6 it is of course possible to provide even more complicated signal combination control.
  • Fig. 7A illustrates the present invention when applied to a spline interpolation circuit which produces four new pixels for each pixel input by using the nearest four pixels for interpolation.
  • the filter coefficients produced by this circuit are approximations of the "Cubic-B Spline" interpolation
  • Fig. 4 illustrates the control signal values necessary to produce the filter interpolation coefficients shown therein.
  • Fig. 8A illustrates the present invention being used as a linear signal mixer which could for example be combining images from two different image sensors or from two different sound or pressure transducers.
  • first stage multiplexers 220 and 222 feed second stage multiplexers 224 and 226 which supply shift divided input signals to adders 228 and 230 which produce/ the linearly mixed output signal.
  • Fig. 8B illustrates the control signal values which produce the indicated linear combinations of the input signals.
  • this can be a programmable set of control signals stored in a ROM or RAM or implemented as an appropriate logic circuit.

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  • Pure & Applied Mathematics (AREA)
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Abstract

Circuit d'interpolation multiplexant les signaux d'entrée avant une ou plusieurs additions au cours du processus d'interpolation afin de réduire le nombre de composants mettant en oeuvre le circuit d'interpolation. Les multiplexeurs appliquent des entrées décalées à un additionneur dans une séquence qui produit les valeurs interpolées à base binaire voulues. Le circuit d'interpolation peut servir à produire de manière programmable des coefficients de filtrage.
EP19910913760 1990-07-09 1991-06-27 Circuit associant de maniere selective les signaux de coefficient de puissance de deux Withdrawn EP0491036A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US54984690A 1990-07-09 1990-07-09
US549846 1990-07-09

Publications (1)

Publication Number Publication Date
EP0491036A1 true EP0491036A1 (fr) 1992-06-24

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP19910913760 Withdrawn EP0491036A1 (fr) 1990-07-09 1991-06-27 Circuit associant de maniere selective les signaux de coefficient de puissance de deux

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EP (1) EP0491036A1 (fr)
JP (1) JPH05501779A (fr)
WO (1) WO1992001260A1 (fr)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5966474A (en) * 1997-12-12 1999-10-12 Hewlett-Packard Company Non-symmetric radial and non-symmetric pruned radial interpolation
US6040926A (en) * 1997-12-12 2000-03-21 Hewlett-Packard Company Common non-symmetric pruned radial and non-symmetric pruned tetrahedral interpolation hardware implementation
US6049400A (en) * 1997-12-12 2000-04-11 Hewlett-Packard Company Non-symmetric tetrahedral and non-symmetric pruned tetrahedral interpolation
US6031642A (en) * 1997-12-12 2000-02-29 Hewlett-Packard Company Tetrahedral and pruned tetrahedral interpolation
US6040925A (en) * 1997-12-12 2000-03-21 Hewlett-Packard Company Radial and pruned radial interpolation
US6028683A (en) * 1997-12-12 2000-02-22 Hewlett-Packard Company Common pruned radial and pruned tetrahedral interpolation hardware implementation

Family Cites Families (4)

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Publication number Priority date Publication date Assignee Title
US4402012A (en) * 1981-11-16 1983-08-30 General Electric Company Two-dimensional digital linear interpolation system
US4783698A (en) * 1987-04-13 1988-11-08 Technology Inc., 64 Interpolator for compressed video data
US4816913A (en) * 1987-11-16 1989-03-28 Technology, Inc., 64 Pixel interpolation circuitry as for a video signal processor
US5043932A (en) * 1989-10-30 1991-08-27 Advanced Micro Devices, Inc. Apparatus having modular interpolation architecture

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9201260A1 *

Also Published As

Publication number Publication date
JPH05501779A (ja) 1993-04-02
WO1992001260A1 (fr) 1992-01-23

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