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WO1996005692A1 - Procede de traitement d'images bitonales video - Google Patents

Procede de traitement d'images bitonales video Download PDF

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Publication number
WO1996005692A1
WO1996005692A1 PCT/EP1995/003143 EP9503143W WO9605692A1 WO 1996005692 A1 WO1996005692 A1 WO 1996005692A1 EP 9503143 W EP9503143 W EP 9503143W WO 9605692 A1 WO9605692 A1 WO 9605692A1
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WO
WIPO (PCT)
Prior art keywords
pixels
fact
image
destination
source image
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.)
Ceased
Application number
PCT/EP1995/003143
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English (en)
Inventor
Marcello Niccolini
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.)
INFOTRONIC SpA
Original Assignee
INFOTRONIC SpA
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 INFOTRONIC SpA filed Critical INFOTRONIC SpA
Priority to EP95929816A priority Critical patent/EP0792552A1/fr
Publication of WO1996005692A1 publication Critical patent/WO1996005692A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/40—Picture signal circuits
    • H04N1/40075—Descreening, i.e. converting a halftone signal into a corresponding continuous-tone signal; Rescreening, i.e. combined descreening and halftoning

Definitions

  • TITLE METHOD OF PROCESSING VIDEO BITONAL IMAGES .
  • the present invention refers to a method for processing bitonal video images.
  • the invention refers to a method for processing and storing bitonal video images including scanned digital matrixes of black and white pixels belonging to an source image (IS) which has to be compressed in order to be transmitted and/or visualised with a reduced number of pixels.
  • IS source image
  • the invention refers also to a device for the realization of the above mentioned method.
  • the documents are scanned with a certain number of so-called pixels.
  • these pixels can be black or white.
  • the resolution for document images reaches also 400 pixels for inch, indicated also with the term “dots per inch", or more shortly, dpi.
  • the sampled bitonal images must be successively stored in a file, from which it must be possible to retrieve and transmit them to a monitor or to trasmit them via facsimile.
  • the CCITT is a committee which defines the various standards for the compression of bitonal documents usually utilized in the documents trasmissions via facsimile or in the images filing.
  • the method "Group 4" performs a better compression than the one of the "Group 3". In spite of that, in case of error in the compressed document the data after the error result to be unretrievable. The method of the "Group 4" is therefore used only with systems free from errors, for istance for the electronic filing of documents.
  • the documents composed of bitonal images should be visualized also on monitors, in particular on a computer monitor.
  • the scaling procedure is effected by a central processing unit CPU (Central Processing Unit) and requires a long time.
  • CPU Central Processing Unit
  • Intel 80x86 such procedure may take even a second and this time is unacceptable for an high quality visualisation and efficient scanning.
  • prior art techniques use different procedures to compress further the image to be processed, but these procedures reduce the image quality and often render it unreadable.
  • the technical problem on which the present invention is based relates to the finding of a method and a device with such characteristics as to allow to scale down a bitonal image and visualise this image on a monitor, in particulkar on a computer monitor, overcoming the limits and/or the disadvantages which are still present in the prior art techniques.
  • the solution idea at the basis of the present invention is the one of performing a processing method of bitonal images which maintains the spatial information of the image, creating an output image with several levels of grey, and which increases at the same time the reading level of the output image itself.
  • FIG. 1 shows schematically a gate architecture for the processing of bitonal images including a device according to the invention
  • FIG. 2 shows schematically the device for the realization of the method according to the invention
  • FIG. 4 shows an example of scaling down a bitonal image performed according to the invention
  • the device 1 includes an image processor IIP which is also indicated with 2 and inserted between a source bus S and a destination bus D.
  • IIP image processor
  • the source bus S conveys all the data referring to the source image IS, that is binary values, corresponding to the bitonal pixels (white/black) .
  • the destination bus ID collects all t,he data referring to the destination image ID, that is values included between 0 and 2*m+l corresponding to pixel at several levels of grey.
  • the source bus S and the destination bus D are DRAM buses (Dynamic Access Memory-bus) .
  • the image processor 2 acts as master of the source bus S when bits corresponding to the source image must be loaded, or it can act as master of the destination bus D when the scaled image rotated at a preestablished angle ⁇ must be written.
  • figure 1 it is globally shown an architecture 10 of a bitonal images processing system including the device 1 with the image processor 2.
  • Such an architecture includes a memory DRAM 37 connected with a decompressor 38.
  • the memory 37 furnishes a stored document in compressed form to the decompressor 38, which provides to store it in a register 39 connected with the source bus S.
  • the destination bus D is connected with a processing unit CPU 40 and with a further register 41 of the VRAM type, which transmits the output data to a look-up table 42, that is to a read only memory.
  • the look-up table 42 provides successively to furnish to a monitor the correct output values, not represented being of a known type.
  • the image processor 2 includes a series of registers, described hereinafter, which must be programmed by the processing unit 40 before the scaling operation starts, according to the invention.
  • the method according to the invention allows to realize a scaling down of a digital image according to a factor n/m, where n and m are positive integers included preferably between 1 and 31 .
  • the maximum scale down factor is 1/31, whilst the maximum scale up factor is 31/1.
  • the document scanned images in digital format have usually resolutions of 200 or 300 dpi, whereas the resolution of a monitor reaches only 120 dpi. It is therefore clear that the images need to be scaled down to be transmitted on a monitor .
  • Figure 4 shows a scaling down example with a resolution of a scanned image according to a scale factor equal to 1:3. This means that a matrix of three by three pixels of a source image IS is converted into one single pixel of a destination image ID.
  • the destination pixel is made black and looses part of the space information of the source image.
  • the matrix of the source image corresponds advantageously a destination pixel with a level of grey corresponding to the ratio between the number of the black pixels and the number of the white pixels.
  • the space information of the source image IS is maintained in the form of intensity of the level of grey in the destination image ID.
  • the method according to the invention works therefore similarly to the human eye, for istance when we look at a figure in a newspaper.
  • the photos published by the newspapers consist of many black and white dots very close together. The dots are so close together that the human eye cannot resolve them individually and perceives the figure as having several levels of grey.
  • the pixels of the source image are first multiplied by a number of times corresponding to the value of the numerator n of the scale factor and added together in scaled groups corresponding to the value of the denominator m of the scale factor.
  • An input I for istance of m binary pixels (black/white) produces an intermediate output 01 of n pixels with values from 0 to m, that is with m+1 levels of grey.
  • the intermediate output 01 is successively vertically scaled adding together the corresponding lines in order to obtain a prestablished number of final output O lines .
  • the final output 0 lines are obtained through the sum of the intermediate output 01 lines and are stored in a temporary line storage buffer.
  • the input binary m lines (white/black) are so changed in output n lines with pixels which have values from 0 to 2*m, that is with 2*m+l levels of grey.
  • the values of the final output O pixels obtained with the above described method are written on the destination bus D in memory addresses* which depend on the rotation angle ⁇ and are sent to the look-up table 42 in order to select the monitor dots and form on it the destination image ID.
  • the image processor 2 includes a register 3 SBBA (Source Bitmap Base Address) which contains the start address of the source image IS bitmap.
  • SBBA Source Bitmap Base Address
  • the processor 2 includes also a register 4 SBP (Source Bitmap Pitch) which contains a "pitch" of the source image IS bitmap, and a register 5 SIW (Source Image Width) which contains the width of the source image IS bitmap.
  • SBP Source Bitmap Pitch
  • SIW Source Image Width
  • the image processor 2 includes also different registers which contain the information concerning the destination image ID and which are listed here below.
  • a first register 6 DBBPP (Destination Bitmap Bits Per Pixel) contains the pixel depth of the destination image ID bitmap.
  • the sizes of the destination image bitmap may be 1,4,8 or 24 bpp (bit per pixel) .
  • a second register 7 DR (Destination Rotation) contains the rotation angle ⁇ of the destination image ID bitmap.
  • rotation angle ⁇ of the destination image bitmap may be either 0, 90, 180,* or 270 degrees.
  • a third register 8 DBBA (Destination Bitmap Base Address) contains the pixel address of the upper left corner of the destination image ID.
  • registers 9 DXF (Destination X Field) and 10 DYF (Destination Y Field) contain respectively the X and Y values concerning the horizontal and vertical sizes of the destination image ID bitmap.
  • a sixth and seventh register 11 DW (Destination Width) and 12 DH (Destination Height) contain respectively the width and the height of the destination image ID.
  • Another register 13 DRO (Destination Raster Operation) contains the codes of sixteen different boolean operations to combine the final output data obtained with the method of the invention with the data already in the destination image ID bitmap.
  • a ninth register 14 HSF (Horizontal Scale Factor) and a tenth register 15 VSF (Vertical Scale Factor) contain the scale factors (that is the two numbers n and m) , which determine how the image is scaled horizontally and vertically.
  • SABSA System Accumulation Buffer Start Address
  • the processor 2 can moreover contain a look-up table 17 including several scale values corresponding to the most common monitors in use.
  • To this series of registers corresponds a series of terminals for the external connection with the source bus S and destination bus D, in order to control the working of the image processor 2 during the scaling operations of a bitonal image.
  • a terminal 18 is connected with a 16-bit bidirectional data bus SData, e a further terminal 19 is connected with a 13- bit bidirectional address bus SAddr and both of them are connected to the source bus S.
  • a terminal 20 and further terminal 21 are connected with a couple of indicators SRas and SCas, which indicate the presence on the address bus SAddr of row addresses or column addresses.
  • a terminal 22 is connected with the read/write line SWE connected with source bus S, and a terminal 23 is connected with the data sampled line SOE connected with the source bus S.
  • a terminal 24 and a further terminal 25 are then connected with the lines SReq and SGnt, which indicate that an external master wants to become or may become master of the source bus S.
  • a terminal 26 is connected with the interrupt signal Int, which is made active whenever the image processor 2 finishes a scaling operation.
  • bus DData connected with destination bus D has 32 bit.
  • connections 33, 34 are designed for the lines DReq and DGnt, which have the task to indicate that the image processor 2 wants to become or may become master of destination bus D.
  • a further terminal 35 is connected with a line DOwn, which indicates when the image processor 2 is master of the destination bus D.
  • a terminal 36 is connected with a line DCS for chip selection, which is used by an external processor to read and write in the inside of the image processor 2 registers.
  • the method according to the invention and the corresponding device for its realization allow to obtain, starting from a source bitonal image IS scanned in a certain number of pixels, a destination image ID compressed according to a scale factor n:m and rotated by an angle ⁇ , maintaining the spatial information in the form of several levels of grey and increasing greatly the legibility of the image self.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Image Processing (AREA)
  • Apparatus For Radiation Diagnosis (AREA)
  • Storing Facsimile Image Data (AREA)
  • Editing Of Facsimile Originals (AREA)

Abstract

L'invention concerne un procédé de traitement et de stockage d'images vidéo bitonales, comprenant des matrices numériques lues par un scanner, de pixels blancs et noirs, faisant partie d'une image source (IS) qui doit être comprimée pour être émise et/ou visualisée avec un nombre réduit de pixels. Selon le procédé présenté, au moins une matrice de l'image source (IS), de taille prédéterminée, est comprimée en un seul pixel de destination, avec un niveau de grille correspondant au rapport entre le nombre des pixels noirs et le nombre des pixels blancs de la matrice. De cette façon, la qualité de l'image est maintenue et sa lisibilité est garantie.
PCT/EP1995/003143 1994-08-09 1995-08-08 Procede de traitement d'images bitonales video Ceased WO1996005692A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP95929816A EP0792552A1 (fr) 1994-08-09 1995-08-08 Procede de traitement d'images bitonales video

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITMI94A001730 1994-08-09
ITMI941730A IT1274608B (it) 1994-08-09 1994-08-09 Metodo di elaborazione di immagini video bitonali e relativo dispositivo

Publications (1)

Publication Number Publication Date
WO1996005692A1 true WO1996005692A1 (fr) 1996-02-22

Family

ID=11369469

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP1995/003143 Ceased WO1996005692A1 (fr) 1994-08-09 1995-08-08 Procede de traitement d'images bitonales video

Country Status (3)

Country Link
EP (1) EP0792552A1 (fr)
IT (1) IT1274608B (fr)
WO (1) WO1996005692A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7809213B2 (en) 2004-02-03 2010-10-05 International Business Machines Corporation Black white image compression having print density control
US7830552B2 (en) * 2005-04-15 2010-11-09 International Business Machines Corporation Black white image scaling having print density control and polarity detection

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0105707A1 (fr) * 1982-09-30 1984-04-18 International Business Machines Corporation Dispositif pour cadrer des données d'images facsimilées
EP0206401A1 (fr) * 1985-06-27 1986-12-30 Océ-Nederland B.V. Procédé pour l'agrandissement/réduction d'une image en demi-teintes
EP0301786A1 (fr) * 1987-07-30 1989-02-01 Crosfield Electronics Limited Traitement d'images

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0105707A1 (fr) * 1982-09-30 1984-04-18 International Business Machines Corporation Dispositif pour cadrer des données d'images facsimilées
EP0206401A1 (fr) * 1985-06-27 1986-12-30 Océ-Nederland B.V. Procédé pour l'agrandissement/réduction d'une image en demi-teintes
EP0301786A1 (fr) * 1987-07-30 1989-02-01 Crosfield Electronics Limited Traitement d'images

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
"Efficient Reduction Algoritm", IBM TECHNICAL DISCLOSURE BULLETIN, vol. 35, no. 7, NEW YORK US, pages 472 - 473, XP000333103 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7809213B2 (en) 2004-02-03 2010-10-05 International Business Machines Corporation Black white image compression having print density control
US7830552B2 (en) * 2005-04-15 2010-11-09 International Business Machines Corporation Black white image scaling having print density control and polarity detection

Also Published As

Publication number Publication date
ITMI941730A1 (it) 1996-02-09
IT1274608B (it) 1997-07-18
ITMI941730A0 (it) 1994-08-09
EP0792552A1 (fr) 1997-09-03

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