principles of coded source imaging using embodiments of the present invention will be described with reference to fig1 . an x - ray tube 100 is adapted not to emit only a single x - ray beam but a multiplicity of spaced apart x - ray beams 102 . the x - ray beams 102 are directed towards an object 104 and transmit the object 104 . the transmitted x - rays are then projected onto an x - ray detector 106 . on a detection surface of the detector 106 , a multiplicity of at least partly overlapping projections of the object 104 by the multiple x - rays 102 is obtained . the detector 106 then transmits the detected image to an image processor 108 . this image processor 108 then derives image information of the object 104 by deconvoluting the detected image using previously provided information about the precise arrangement and dimensions of the multiple x - rays 102 emanating from the x - ray tube 100 . thereby , a final image 110 of the object 104 may be obtained wherein the final image has a high resolution which is mainly limited by the quality of one single of the multiplicity of x - rays 102 but not on the envelope of the x - ray distribution provided by all of the x - ray beams 102 . fig2 shows an embodiment of an electron emitter 1 . the electron emitter 1 comprises a cathode 3 and an anode 5 . the cathode 3 comprises a substrate 7 which on one surface thereof comprises an electron emission pattern 9 including spatially separated local areas 11 . the cathode 3 and the anode 5 are connected to a voltage source 13 . the local areas 11 are adapted such that upon application of a voltage to the anode 5 and the cathode 3 , electrons are emitted from the local areas via field emission . for this purpose , the local areas may be made of a specific material having a small work function so that electrons may relatively easily exit from a surface of the material of the local areas 11 . alternatively or additionally , the local areas 11 may be provided with a rough surface such that at edges or needles of the surface of the local area , the electric field between the anode 5 and the cathode 3 is locally enhanced . for example , the local areas may be covered by a layer of carbon nanotubes which are preferably arranged vertically adjacent to each other so as to form a very rough surface in a direction towards the anode 5 . regions in between the local areas 11 and separating these local areas 11 spatially are adapted such as to emit no or at least only a few electrons via field emission . accordingly , these intermittent regions may have a different material or a different surface structure such as for example an even surface . electrons emitted from the local areas 11 via field emission are then accelerated towards the anode 5 forming electron beams 15 . these electron beams 15 may be transmitted through the mesh - like anode 5 and may travel further towards a target of an x - ray tube ( not shown in fig2 ). there , the impacting electron beams 15 may generate respective spaced apart x - ray beams . fig3 shows an alternative embodiment of an electron emitter 1 ′. therein , the anode 5 ′ is provided as a ring anode 5 ′. electron beams 15 may be transmitted through an inner opening 17 of the ring - anode 5 ′. fig4 shows an alternative embodiment of an electron emitter 1 ″. therein , the anode 5 also serves as an x - ray target 19 . electron beams 15 emitted from local areas 11 on the cathode 3 are accelerated towards the anode 5 by a voltage applied between the anode 5 and the cathode 3 using the voltage source 13 . in this embodiment , the anode 5 is made of a thin foil of tungsten . upon impact of the electron beams 15 on the foil of the anode 5 , the electrons are decelerated within the foil thereby generating bremsstrahlung which is transmitted through the foil and emitted as x - ray beams 102 on an opposite side of the anode . accordingly , the anode 5 serves also as an x - ray target 19 . fig5 schematically shows an x - ray image acquisition device 200 according to an embodiment of the present invention comprising an electron emitter 1 ″ similar to the one shown in fig4 . x - ray beams 102 generated at the anode / target 5 / 19 of an x - ray tube 100 ′ are emitted towards an object 104 to be observed . the x - rays 102 transmitted through the object 104 are then projected onto an x - ray detector 106 . the detector 106 detects an overall image comprising overlapping sub - images of the separate x - rays 102 . the overall image is then transmitted to an image processor 108 where it is deconvoluted in order to generate the final image 110 . for the purpose of this decon - volution , it may be important to know the x - ray intensity distribution emitted at the target 19 or , as this x - ray intensity distribution depends on the arrangement of the local areas 11 in the electron emitter 1 ″, to have precise information about the arrangement and dimensions of the electron emission pattern 9 comprising the local areas 11 . fig6 and 7 show alternative embodiments of an electron emitter 1 ′″ and of an x - ray image acquisition device 200 ′. therein , the anode 5 ′ is provided as a solid wedge thereby creating a slanted target 19 ′. electron beams 15 coming from the local areas 11 impact onto this slanted target 19 ′ from one side of the target 19 ′ and bremsstrahlung is created . this bremsstrahlung is emitted as x - rays at the same side of the slanted target 19 ′ but an angle of approximately 90 ° with respect to the direction of the electron beams 15 . the x - ray beams 102 are then transmitted through an object 104 and detected on an x - ray detector 106 which finally transmits the detection result to an image processor 108 . fig8 and 9 show schematically top views onto the surface of a cathode 3 of an electron emitter 1 according to an embodiment of the present invention . in fig8 , the electron emission pattern 9 is a simple matrix of singular local areas 11 arranged in lines and rows . therein , the width w of a local area 11 is significantly smaller , for example less than a half , than the distance s between adjacent local areas 11 . of course , the local areas 11 do not have to be rectangular but can have any suitable shape . for the deconvolution of the final image within the image processor 108 it may be important to have precise information about the entire geometry of the electron emission pattern 9 , particularly about the shape of the local areas 11 , about their lateral dimensions such as the width w and about the distance s between respective adjacent local areas 11 . furthermore , information should be available as to how the geometry of the electron emission pattern 9 is projected via the field - emitted electron beams 15 onto a target 19 in order to have information about the lateral x - ray intensity distribution generated at such target 19 . fig9 shows an alternative example of an electron emission pattern 9 ′ realized as uniform redundant arrays . fig1 shows , in its upper graph , an intensity distribution 21 of electrons emitted by the electron emission pattern 9 shown in fig8 along the line a - a in fig8 . it can be seen that an electron intensity is maximum in the regions of the local areas 11 whereas in the intermittent spacing regions , an electron intensity is almost zero . accordingly , the distribution of electron beams along the lateral surface of the electron emitter 1 strongly corresponds to the electron emission pattern 9 . in the lower graph of fig1 , an intensity distribution 23 of x - rays generated by electrons emitted by the electron emitter 1 impacting onto a target 19 is shown along the line a - a of fig8 . it can be seen that the x - ray intensity distribution 23 still has a good correlation to the geometry of the electron emission pattern 9 . fig1 shows a c - arm x - ray system representing an example of an x - ray image acquisition device 200 . an x - ray source 100 and a detector 106 are arranged at a c - arm 112 which may be translated and pivoted with respect to an object 104 . data of the detector may be transferred to an image processor 108 . finally , it should be noted that the terms “ comprising ”, “ including ”, etc . do not exclude other elements or steps and the terms “ a ” or “ an ” do not exclude a plurality of elements . also , elements described in association with different embodiments may be combined . it should also be noted that reference signs in the claims should not be construed as limiting the scope of the claims .