a preferred embodiment of the invention is illustrated in the cross - sectional view of fig1 of a substractive color display 10 . the display 10 includes three levels 15 , 17 , 19 or cells , where each cell has an active matrix 36 , 38 , 40 and a liquid crystal material 30 , 32 , 34 , respectively . the active matrix for each level operates in the manner described in greater detail in u . s . pat . application ser . no . 07 / 872 , 297 filed on apr . 22 , 1992 . the three liquid crystal levels 30 , 32 , 34 where each contain a dye . cell 15 , for example , can contain a magenta dye , cell 17 can contain a cyan dye and cell 19 can contain a yellow dye . other colors can also be used to provide a substractive color system . by stacking the three levels in serial registration , the cells form a subtractive full color active matrix display in which single crystal or essentially single crystal layers of silicon are used in each active matrix area to provide the pixel and circuits and electrodes of each pixel element of the display . the peripheral regions 12 , 14 , 16 of each single crystal layer , in which the active matrix of thin film transistors is also formed , contains cmos driver circuitry to drive the rows and columns of each active matrix . the upper cell 15 has liquid crystal material 30 sandwiched between upper transmissive superstrate 24 and substrate 18 . the middle cell 17 has upper superstrate 26 and substrate 20 and the lower cell 19 has superstrate 28 and substrate 22 . a broad band light source directs light 42 through substrate 22 . each cell , in selective combination with the other cells can remove selected spectral bands of light from incident light 42 to produce a selected image exiting the display at superstrate 24 . polarizing plates ( not shown ) are inserted into the stack of cells to define the polarization of light being transmitted through display 10 . another preferred embodiment is illustrated in fig2 where a three layer stack of cells is formed . three layers of liquid crystal material 60 , 62 , and 64 are positioned adjacent to three active matrix arrays 66 , 68 , and 70 , respectively . an adhesive can be used to join the three cells at 82 , 84 and 86 , respectively . electrical and / or optical interconnects can be used in drive circuit layer elements 90 , 92 and 94 formed on both sides of the display . for example , electrical interconnect 78 serves to electrically connect circuit 90 and 92 . electrical interconnect 80 is used to electrically connect circuit elements 92 and 94 . additionally , light emitting and detector elements 72 , 74 and 76 can be formed in or on circuits 90 , 92 and 94 , respectively . the light emitting components can be led &# 39 ; s , lasers , or electroluminescent elements for example . the light from elements 72 , 74 and 76 can be conducted through substrates 54 , 56 and adhesive layers 82 , 84 and 86 . optical waveguides such as optical fibers 88 or fiber optic plates can also be used . a further embodiment is shown in fig2 a where two active matrix arrays 95 , 97 are formed on opposite side of substrate 83 . the matrix arrays 95 , 97 can be formed along with peripheral drive circuitry 93 and 91 , respectively , in thin films of single crystal silicon and transferred onto opposite sides of substrate 83 using techniques described in the above referenced related applications . optically transmissive superstrates 81 and 85 can then be secured by an adhesive to substrate 83 to form cavities in which a liquid crystal material 99 can be inserted . the material 99 in each cavity can contain different colors to provide a multicolor display . a third active matrix can be aligned over superstrate 81 to provide a third cavity in which a third color liquid crystal material can be inserted to provide a full color display . a process sequence is shown in fig3 a - 3e for forming a plurality of subtractive color displays on a single semiconductor wafer or substrate . a single crystal silicon substrate 100 is provided as shown in fig3 a on which an insulating layer 102 , such as an oxide , is formed . a single crystal silicon layer 104 can be formed over the oxide 102 by several known processes including recrystallization of an amorphous or polycrystalline silicon layer . active matrix elements 106 , 108 and 110 are formed in layer 104 as shown in fig3 b . drive circuitry ( not shown ) can also be formed in layer 104 for each active matrix of each display as described in connection with fig2 a . a second level of active matrix elements 120 , 122 and 124 are formed , and transferred onto optically transmissive substrates 112 , 114 and 116 which are aligned over matrix elements 106 , 108 and 110 . a third level of active matrix elements 136 , 138 and 140 are formed and transferred onto substrates 130 , 132 and 134 as shown in fig3 c . matrix elements 136 , 138 and 140 are aligned with underlying matrix elements . optically transparent superstrates 142 , 144 and 146 are then mounted over each display as shown in fig3 d . cavities 150 , 152 and 154 have been provided during fabrication in which liquid crystal material can be inserted either just after cavity formation or after further processing of the display . substrate 100 can then be removed by an etching procedure 148 described in the above referenced parent applications . all three displays can then be mounted on a single substrate to form a multi display system , or as shown in fig3 e , separate displays 170 , 172 and 174 can be mounted on transparent substrates 156 , 158 and 160 . another preferred embodiment of the invention relates to an improvement in liquid crystal display employing two active matrix arrays on opposite sides of a liquid crystal material as illustrated in fig4 . standard displays limit the electric field to directions perpendicular to the electrodes of the display . in such a pixel , the polarization can be rotated by hanging the potential across the electrodes . this yields only one degree of freedom in the control of light through the pixel . usually , this degree of freedom is used to control greyscale . fig4 illustrates a system that broadens the number of degrees of freedom in the electric field to three where a second active matrix 150 is aligned opposite the first active matrix 152 around liquid crystal 158 . the active matrix arrays 150 and 152 are mounted onto transparent substrates 154 and 156 respectively . each display pixel 162 comprises six electrodes ( two shown ) which can be biased to create an electric field that has components in three axes . thus , in addition to electric field strength ( which can be used to control greyscale ), the field direction can be altered . the three degrees of freedom in the electric field can be used to select colors , and thereby transform a single monochrome display cell into a color display cell . fig5 illustrates one way in which this can be achieved . three polarized light sources 184 , 186 and 188 ( red , green , and blue ) are oriented such that the light approaches the lcd 180 in orthogonal directions . the display cell has a top diffuser 182 . the electric field is then oriented so that it is parallel to one of the colors and perpendicular to the other colors , and in this way selects the light source . by shifting to other orthogonal directions , other light sources can be selected . by appropriately choosing an intermediate direction with components is all directions , a particular color can be selected . the field direction is determined by the relative potentials applied to the electrodes . the field strength ( the magnitude of the components ) can be adjusted without changing the relationship between the potentials and thus without changing the field direction . thus , greyscale and color selection can be attained . this type of color display pixel has advantages over the color filter approach , the main advantage is that the pixel has much higher aperture , owing to the separation of light into components before incidence on the lcd . for example , in a conventional color filter lcd , white light is equally incident on red , green , and blue filters . each filter receives one third of the incident light , and each filters out an additional two - thirds in the full - on condition . for example , the blue filter rejects all incident red and green light , making the best - case throughput 33 %. thus , in the full on state , the color filter approach has an optical throughput of 33 %. for single color operation , the throughput is one third , or 11 %. the pixel system described here has a throughput of 33 % for single color operation and about 70 % for the full on condition . the double matrix approach has other advantages when used in conventional approach . these include ( 1 ) enhanced greyscale , ( 2 ) enhanced reliability and ( 3 ) enhanced contrast ratio . in addition , the second matrix 150 can be used to correct for nonuniformities , or to add an overlay of a second image onto a first image generated by the first active matrix 150 . while this invention has been particularly shown and described with reference to preferred embodiments thereof , it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention are defined by the appended claims .