GB2330446A - Editing image data - Google Patents

Abstract

Image data representing image frames are edited. Segment data is stored and image frames are displayed in response to this segment data. A visual display displays visual elements 304,305 representing adjoining image segments in response to the segment data. A manual input device selects and adjusts transitions between adjoining segments so that the segment data is modifiable in response to these adjustments. The system is configured to selectively operate in a linked mode or in an unlinked mode. In the linked mode, movement 314 of a transition 315 between adjoining segments maintains the segments as being adjoining by adjusting the lengths of both of the segments. In the alternative unlinked mode, movement of a transition results in the length of one of the segments 305 being modified while its adjoining segment 304 retains its original segment length.

Description

Editing Image Data The present invention relates to an apparatus for editing image data representing a plurality of image frames. The present invention also relates to a method of editing image frames.

Systems are known for editing image data in which the data is represented by digital data samples. In the majority of systems, editing of this type is performed on a low resolution version of the data, allowing the operations to be performed using relatively modest equipment. At the end of an editing session, the system is configured to produce a machine readable edit decision list which may then be used to control an on-line editing operation at full definition.

Systems which provide for the editing of images in the form of machine readable data allow the data to be accessed from disc such that an editor may quickly move to a particular frame without running through the entire length of a tape. In this way, the perceived distance between frames is non-linearly related to their temporal displacement along a notional reel, usually represented by timecode, and for this reason systems of this type are often referred to as being "non-linear".

Non-linear editing suites provide many advantages over traditional editing methods and a demand has therefore been created for providing nonlinear facilities at full definition, thereby providing non-linear on-line editing.

Such facilities are required to handle video clips at full definition and as such require significant levels of storage in combination with highly powered data processing engines. Consequently, the overall cost of such systems, when compared to similar off-line environments, is relatively high therefore on-line editing procedures need to be performed quickly and accurately, with many tools being made available to an operator, thereby making the overall procedures as efficient as possible.

When editing clips of cinematographic film, the clips are made physically available to an editor and as such may be manipulated independently until a physical join is made as part of the editing process. In a non-linear editing environment, clips are merely represented on a visual display unit and all manipulations to these clips must be implemented using manually controllable interface devices. Thus, in known environments, situations exist in which operations performable upon physical lengths of cinematographic film or physical lengths of video tape do not immediately have a parallel within the non-linear editing environment.

According to a first aspect of the present invention, there is provided an apparatus for editing image data representing a plurality of image frames, comprising storage means for storing segment data; output means for displaying image frames in response to said segment data; visual display means for displaying visual elements representing a joining of image segments in response to said segment data; manual input means for selecting and adjusting transitions between joining segments such that said segment data is modifiable in response to said adjustments; and processing means configured to selectively operate in a linked mode or in an un-linked mode, such that in said linked mode movement of a transition between adjoining segments maintains said segments as being adjoining by adjusting the lengths of both of said segments, and in said un-linked mode movement of a transition results in the length of one of said segments being modified while its adjoining segment retains its original segment length.

In a preferred embodiment, the storage means is configured to store a data block for each segment, including a start time and an end time for said segment. A processing means may be configured to update two data blocks when segments are linked and configured to update only one data block when said segments are un-linked.

According to a second aspect to the current invention, there is provided a method of editing image data representing a plurality of image frames, comprising steps of storing segment data; displaying image frames in response to said segment data; displaying visual elements representing adjoining image segments in response to said segment data; selecting and adjusting transitions between adjoining image segments such that said segment data is modifiable in response to said adjustments; and selectively operating in a linked mode or in an un-linked mode, such that in said linked mode movement of a transition between adjoining segments maintains said segments as being adjoining by adjusting the lengths of both of said segments, and in said un-linked mode movement of a transition results in the length of one of said segments being modified while its adjoining segment retains its original segment length.

In a preferred embodiment, movement data is converted into representations of timecode. Preferably, an attribute of a displayed icon is changed in dependence upon a selected mode of operation.

The invention will now be described by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows an on-line non-linear editing suite, having a processing unit, a frame storage device, a visual display unit and manually operable input devices; Figure 2 illustrates operations performed within the edit suite identified in Figure 1, including the editing of video clips; Figure 3 illustrates modifications to a video clip; Figure 4 illustrates an image display to an operator while performing a linked edit; Figure 5 illustrates an image shown to an operator during an un-linked edit; Figure 6 illustrates the formatting of segment data within a track file; Figure 7A, 7B and 7C illustrates the editing of frames within a clip; Figure 8 details the editing of track segments identified in Figure 2, including a step for updating segment data; Figure 9 details the segment updating step identified in Figure 8 for linked edits; Figure 10 illustrates the updating of the data shown in Figure 6 in response to the procedures shown in Figure 9; Figure 11 details the updating of segment data in the unlinked mode; and Figure 12 shows the updating of the data shown in Figure 6 in response to the procedure identified in Figure 11.

An on-line editing facility is shown in Figure 1, in which video source material is captured from video tape 101 via digital video tape recorders 102.

The capturing process involves the transfer of the video material to an array of magnetic disk storage devices 103, in which full definition video signals are transferred in real time by a process of striping video images across a plurality of disk drives.

The transfer of information and the processing of data occurs within a computer 104 such as an ONYX manufactured by Silicon Graphics Inc. and including executable instructions for performing editing functions in response to operator commands. These executable instructions may be loaded into the ONYX system by means of a suitable computer readable medium, such as CD ROM.

Operator commands are generated by a stylus 105, a keyboard 106 and a mouse 107. Video images are displayed on a visual display unit 108 which presents the video clips and other graphical information within a graphical user interface. In addition, video images may also be supplied to a broadcast quality monitor 109 with audio signals being supplied to loudspeakers 110 and 111.

Operations performed by the editing environment identified in Figure 1 are detailed in Figure 2. At step 201 an edit decision list is loaded to processing system 104, usually by inserting a floppy disk or, alternatively, by receiving an EDL file over a data network.

In response to commands within the edit decision list, an operator is prompted to insert appropriate video tapes 101 into a video tape recorder so that the processing system 104 and the disk array 103 may perform a capturing process at step 202.

After the data has been captured, the edited video is displayed to the operator on visual display unit 108 in the form of track segments at step 203.

At step 204 track segment edits are performed in response to operator commands and after making these edits, video material is previewed at step 205. The previewing of video material is displayed on the visual display unit 108 and is also displayed on monitor 109. In addition, any audio tracks associated with the video may be directed to loudspeakers 110 and 111.

Thus, the environment provides a facility in which editing operations may be performed on both the video track and the audio tracks.

A question is asked at step 206 as to whether the preview has been successful and if answered in the negative, steps 204 and 205 may be repeated. By answering the question at 206 in the affirmative, the newly created video material may be recorded on a new video tape using one of the video tape recorders 102.

The editing of track segments at step 204 allows the segments to be edited in one of several selectable modes of operation, to be described subsequently. The editing apparatus is arranged to represent many image frames which are stored at full definition on the disk array 103. In addition, a representation of these frames is stored as segment data within the processing system 104 using its own local storage facilities. An output is generated by processing system 104 which is supplied to the visual display unit 108 representing image frames in response to the stored segment data.

Thus, segments displayed on visual display unit 108 may be modified resulting in an appropriate display of video data from disk storage 103. Visual display unit 108 displays visual elements representing adjoining image segments in response to the segment data stored by the processing system 104. An operator uses stylus 105 or mouse 107 to select and adjust transitions between adjoining segments resulting in the segment data stored by processing system 104 being modified.

The processing system 104 includes executable instructions arranged to configure the system such that it may selectively operate in a link splice mode or in an unlink splice mode. In the link splice mode, movement of a transition between adjoining segments maintains the segments as being adjoining by adjusting the lengths of both of the segments. However, in the unlink splice mode, movement of a transition results in the length of one of the segments being modified while its adjoining segment retains its original length.

These modes of operation are illustrated in Figure 3, which illustrates the operation of the system but does not reflect the way in which the information is actually displayed on the visual display unit 108.

An original splice or cut is illustrated at 301, an edit to this cut in link splice mode is shown at 302 and a similar edit in unlink splice mode is shown at 303. At 301 a segment 304 from a first source has been spliced to a similar segment 305 from a second source. Regions 304 and 305 represent the actual video frames that will be displayed in the original output material. In order for edits to be effected upon these clips, it is necessary for adjoining frames to be included such that the point at which the cut occurs may be advanced or retarded as is considered appropriate. Consequently, each segment, such as segment 304, includes handles 306 and 307. In this way, cut 308 representing the point at which segment 304 starts may be advanced by including additional frames within portion 304 taken from leading handle 306. Similarly, cuts 309 between segments 304 and 305 may be retarded, with reference to segment 304, by increasing the length of segment 304 by taking frames from the trailing handle 307. Similarly, segment 305 is provided with a leading handle 310 and a trailing handle 311.

In this example, it is assumed that an edit decision has been made to the effect that cut 309 should be moved from position 312 to position 313 as indicated by arrow 314. In the link splice mode of operation, cut 309 is selected and moved to position 315 as shown at 302. This results in trailing handle 307 being increased while leading handle 310 is reduced. Clearly, the extent to which this cut may be moved in the direction of arrow 314 will depend upon the length of leading handle 310 and appropriate capture hints may be given during the capturing process to ensure that edits of sufficient size may be effected.

In some circumstances, it may be desirable to modify segment 304 without making any changes to adjoining segment 305. Under these circumstances the unlink splice mode of operation may be selected as illustrated at 303. Again, segment 304 is selected for editing such that its duration is reduced and frames previously contained within segment 304 are effectively transferred to the segment's trailing handle 307. However, as shown at 303 in the unlink splice mode, the length of segment 305 remains unchanged and the length of its leading handle 310 also remains unchanged.

This effectively results in a gap 316 being introduced between what were previously adjoining clips 304 and 305.

In the preferred embodiment, blank frames are introduced into a gap such that the edited results may be previewed at step 205. Subsequently, new material may be introduced into this gap or other appropriate editing functions may be performed. However, the unlink splice mode of editing has ensured that modifications effected to segment 304 do not result in any modifications being made to segment 305.

An example of images displayed on visual display unit 108 is shown in Figure 4. Video images for preview purposes are shown within a window 401 and a particular image clip may be displayed at video rate in response to soft button 402 of the graphical user interface being selected. Soft button 403 allows new segments of video to be introduced, possibly as a result of effects being generated as on-line operations.

Linked splice editing may be selected by activation of button 404 with unlinked splice editing being selected in response to deactivation of button 404. An additional Link Transition mode of editing may be selected by activation of soft button 405. Thus the soft button interface illustrated in Figure 4 provides a possibility of four modes of operation: Link Splice and Link Transition both off; Link Splice on with Link Transition off; Link Splice off with Link Transition on, and Link Splice on with Link Transition on.

In the example shown in Figure 4, link splice editing has been selected, resulting in button 404 being highlighted as illustrated by boundary 406. In response to link splice editing being selected a cursor 407 of an appropriate colour is displayed and said cursor moves in response to manual movement of the stylus 107.

In response to movement of the stylus 107, cursor 407 moves allowing a particular edit cut, such as cut 408 to be selected. The cut is edited by placing the stylus 107 into pressure and while held in this state, the cut point can be moved in the direction of arrows 409. Thus, in this way, the cut is displayed as movement horizontally in either direction to perform a link splice edit as illustrated at 302.

A similar situation is shown in Figure 5 in which the link splice button 404 is deselected. Upon deselecting the link splice button, a differently coloured cursor is displayed on the monitor, which may consist of a single arrow 502. The direction of arrow 502 indicates which of the two video segments will actually be modified. In the example shown in Figure 5, the arrow is directed towards the left such that segment 503 is edited while segment 504 remains unchanged. As shown in Figure 5, the edit cut has been moved to the left, resulting in a gap 505 being introduced between segments 503 and 504.

The processing system 104 is configured to store segment data and the structure of this data is illustrated in Figure 6.

Edit decision list data received by the system is converted into a track 601. Within the track file particular segments are named by a segment name 602. In the example shown in Figure 6, segment name 602 identifies "segment 075" with segment name "segment 076" being identified at 603.

Segment data associated with segment name 602 is shown at 604 with similar data with respect to segment 076 being shown at 605. For the purposes of this example, it is assumed that segment 304 shown in Figure 3 is derived from segment data 604 and segment 305 is derived from segment data 605.

The segment data contains a total of six timecodes 606, 607, 608, 609, 610, 611. Timecode 606 represents the start of the clip in memory and would therefore represent the earliest timecode of leading handle 306.

Similarly, timecode 607 represents a last frame stored in memory and as such is represented by the highest timecode of trailing handle 307.

Timecodes 608 and 609 represent the proportion of the video clip which is actually being contained in the output. Thus, timecode 608 represents the first frame of segment 304 with timecode 609 representing the last frame of this segment.

An output clip derived from the segments shown in Figure 6 is illustrated in Figure 7A. The output clip runs from 00:23:14:08 (abbreviated to 14:08) to 15:23. Frames 14:08 to 14:22 are derived from reel 52 with frames 14:23 to 15:23 being derived from reel 17.

The effect of a 10 frame link splice edit to the left is illustrated in Figure 7B. The output clip still commences at 14:08 and ends at 15:23. However, the edit point has been moved to the left, in link splice mode, such that reel 52 now terminates at frame 24:09 with reel 17 commencing at frame 51:23.

A similar edit in unlinked splice mode is illustrated in Figure 7C. Again, the output portion of the clip is written to output frames 14:08 to 15:23 the system being such that 24 frames are present within each second of a clip.

The same editing action is performed such that the cut point is moved 10 frames to the left and the clip taken from reel 52 finishes at frame 24:08.

However, the start of reel 17 remains at frame 52:09 and the 10 intermediate frames 701 are effectively left blank and are derived from copies of a null frame.

Procedures for performing an edit are illustrated in Figure 8. At step 801 activation of a pointing device, such as a mouse click or the putting of a stylus into pressure, is detected.

At step 802 the selected edit is identified in terms of the edit cut point.

At step 803 movement data is obtained representing movement of the edit cut point and in response to this movement the segment data is updated at step 804. At step 805 a question is asked as to whether the pointing device has been de-activated and if this question is answered in the negative control is returned to step 803.

Eventually, the editor will position the cut point at the required position resulting in the question asked at step 805 being answered in the affirmative, thereby allowing the edited material to be previewed in accordance with step 205.

The updating of segment data at step 804 will result in a function call, the exact nature of which will depend upon whether link splice mode or unlink splice mode has been selected.

The appropriate function for link splice mode is illustrated in Figure 9.

At step 901 the movement data is converted into a frame movement FM and at step 902 a question is asked as to whether the movement has been to the left. If answered in the affirmative, the reducing segment, that is the segment to the left, is reduced by the frame movement FM at step 903.

Similarly, the increasing segment to the right is updated by the frame movement at step 904.

If the question asked at step 902 is answered in the negative, to the effect that the edit position has been moved to the right, the reducing segment, to the right, is updated at step 905 and the increasing segment to the left is updated at 906.

The effect of the function shown in Figure 9 upon the track data shown in Figure 6, is illustrated in Figure 10. Steps 903, 904, 905 and 906 result in segment data being identified within a track file and updated in accordance with the specified edit, such as the example shown in Figure 7A. Thus, the particular segments being edited are known to the process resulting in an appropriate index being generated into the track file 601. Within the track file the particular segment data under consideration is identified and the particular timecode is similarly indexed within the segment portion. Following this procedure, as shown in Figure 10, the timecode at location at 609 is reduced by ten frames as shown at 1003. Similarly, the start of the output timecode is reduced by ten frames as shown by 1004.

In accordance with the link splice mode of operation, as a clip length is reduced in response to an edit cut being removed, its adjoining clip is increased. Consequently, reel 17 starts at timecode 51:23 as shown at 1005 with output frames being written to position 14:13 as shown at 1006.

Similar modifications would be effected if the question asked at step 902 were answered in the negative. This would result in all the modified timecodes being increased instead of being decreased.

Procedures 804 for up-dating segment data in un-link splice mode are detailed in Figure II. At step 1101 the frame movement FM is identified at and step 1102 a question is asked as to whether this movement is to the left.

If answered in the affirmative, control is directed to step 1103, alternatively control is directed to step 1107.

At step 1107 the reducing left segment data is up-dated and at step 1104 the question is asked as to whether a blank segment has been introduced. If this question is answered in the negative, a blank segment is created at step 1105 whereafter at step 1106 the blank segment data is itself updated. If the question asked at step 1104 is answered in the affirmative, control is directed to step 1106.

Similarly, if the question asked at step 1102 is answered in the negative, to the effect that the movement is been to the right, the right segment data is up-dated at step 1107. The question is then asked as to whether a blank segment has been introduced at step 1108 and if answered in the negative control is directed to step 1109. At step 1110 the blank segment is updated and control is then directed to step 805. If the question asked at step 1108 is answered in the affirmative, the existing blank segment data is up-dated at step 1110.

The effect of using the function detailed in Figure 11 as defined by the edit detailed in Figure 7C is shown in Figure 12. Segment 075 is updated substantially as for the previous edit in that the timecode at 609 is reduced to 24:09 and the timecode at 611 is reduced to 14:12.

The data contained within segment 076 is unmodified but renumbered as segment 077 with a new segment 076 being introduced to contain the blank data. Thus, the blank data segment (new 076) would be introduced in response to operation 1105 with frames being taken from a notional reel 500 containing ten hours of blank data. In practice, all of these frames would be obtained from the same frame source but the numbering of notional timecodes maintains the integrity of the system. Blank frames 00:01 to 00:10 effectively become part of the output over the range 14:13 to 14:22.

Prior to this, up to 14:12, frames are derived from reel 52 and after this, from 14:23, frames are derived from reel 17.

In the preferred embodiment, an additional mode of operation is provided by activation of the Link Transition soft button 405 as illustrated in Figures 4 and 5. A transition segment defines a process for smoothly transferring from outgoing to incoming segments. A transition segment is defined, that overlaps outgoing and incoming segments, and the Link Transition mode affects how this transition segment responds to splice editing operations. The Link Transition mode of operation is illustrated in Figure 13. An original splice or cut is illustrated at 1301. An edit to this cut in unlinked transition mode is shown at 1302, and a similar edit in link transition mode is shown at 1303. At 1301, a segment 1304 from a first source has been spliced to a similar segment 1305 from a second source. A shaded region 1351 defines a transition segment, which combines frames from both outgoing and incoming segments 1304 and 1305 respectively. The transition segment 1351 enables a sequence of overlapping frames to be defined, during which a transition effect may be applied. A typical transition effect is the application of a crossfade or dissolve. More complex transition processes include iris effects, with the incoming image appearing in the centre of the screen, and progressively opening up to fill the screen by the end of the transition segment 1351.

The handles 1306, 1307, 1310 and 1311 on each segment provide the frames that are required for transition effects, as well as ensuring that sufficient frames are available when moving a splice point in linked mode, as indicated at 302 in Figure 3. An example of moving the end of segment 1304 in unlinked mode, while a transition effect is applied, is shown at 1302. In this example, segment 1304 ends before the transition effect commences.

Consequently, the transition effect results in a crossfade from black frames to the frames of segment 1305. The example shown at 1302 is useful, as it enables additional material to be inserted in the gap that remains, with the transition effect automatically taking effect upon the newly inserted segment without the need for further editing operations.

An example of performing the same splice movement in link transition mode is shown at 1303. In this example, the transition segment 1351 has moved with the splice point. In the unlinked transition mode, the transition segment is unlinked to the splice point. Thus, the transition segment will remain fixed in position on the timeline, until deliberately moved, regardless of the movements of splice points that are carried out with respect to other segments.

The examples hitherto described have made the assumption that modification of a start or end to a segment results in a selection of a different frame in the segment being selected as the first or final frame. In an alternate mode of operation, modification of a splice point or start or end point of a segment does not result in a different frame being selected, in other words, an entire sequence of frames in the modified segment or segments will be shifted in time. This is illustrated in Figure 14. At 1401 an outgoing segment 1404 is spliced at 1407 with an incoming segment 1405. The first frame of the incoming segment 1405 is indicated at 1406. In the mode of operation universally assumed in previous examples, the result of moving a linked splice point to the right is shown at 1402. In this instance the first frame 1406 of the incoming segment 1405 has been shifted into the handle of the incoming segment 1405, and the remainder of the frames in that segment remain in the same position with respect to the timeline. At 1403, the same splice operation has been carried out in the alternate mode of operation where the frames of segments are fixed in position relative to the splice point 1407. In this instance, the first frame of the incoming segment 1405 is still frame 1406, although the splice point has moved. Thus, it will have been necessary to shift all frames in the segment with respect to the splice point.

In a further altemate embodiment, gaps created as a result of moving a splice in unlinked mode are considered as segments themselves, with appropriate manipulations being applicable thereto. Furthermore, the default setting of blank, black frames may be modified by the user to frames having any desired specifiable characteristic.

Claims (19)

Claims

1. Apparatus for editing image data representing a plurality of image frames, comprising storage means for storing segment data; output means for displaying image frames in response to said segment data; visual display means for displaying visual elements representing adjoining image segments in response to said segment data; manual input means for selecting and adjusting transitions between adjoining segments such that said segment data is modifiable in response to said adjustments; and processing means configured to selectively operate in a linked mode or in an unlinked mode, such that in said linked mode movement of a transition between adjoining segments maintains said segments as being adjoining by adjusting the lengths of both of said segments, and in said unlinked mode movement of a transition results in the length of one of said segments being modified while its adjoining segment retains its original segment length.

2. Apparatus according to claim 1, wherein said storage means is configured to store a data block for each segment, including a start time and an end time for said segment.

3. Apparatus according to claim 2, wherein said processing means is configured to update two data blocks when segments are linked and said processing means is configured to update only one data block when said segments are un-linked.

4. Apparatus according to any of claims 1 to 3, wherein said processing means is configured to convert movement data into representations of timecode.

5. Apparatus according to any of claims 1 to 4, wherein said processing means is configured to change displayed attributes depending upon the mode of operation.

6. A method of editing image data representing a plurality of image frames, comprising steps of storing segment data; displaying image frames in response to said segment data; displaying visual elements representing adjoining image segments in response to said segment data; selecting and adjusting transitions between adjoining image segments such that said segment data is modifiable in response to said adjustments; and selectively operating in a linked mode or in an un-linked mode, such that in said linked mode movement of a transition between adjoining segments maintains said segments as being adjoining by adjusting the lengths of both of said segments, and in said un-linked mode movement of a transition results in the length of one of said segments being modified while its adjoining segment retains its original segment length.

7. A method according to claim 6, wherein a data block is stored for each segment and each data block includes a segment start time and a segment end time.

8. A method according to claim 7, wherein two data blocks are updated when operating in said linked mode but only one data block is updated when operating in said un-linked mode.

9. A method according to any of claims 6 to 8, wherein movement data is converted into representations of timecode.

10. A method according to any of claims 6 to 8, wherein an attribute of a displayed icon is changed in dependence upon a selected mode of operation.

11. A computer readable medium having computer-readable instructions executable by a computer such that said computer performs the steps of: storing segment data representing image frames; displaying image frames in response to said segment data; displaying visual elements representing adjoining image segments in response to said segment data; selecting and adjusting transitions between adjoining image segments such that said segment data is modifiable in response to said adjustments; and selectively operating in a linked mode or in an unlinked mode, such that in said linked mode movement of a transition between adjoining segments maintains said segments as being adjoining by adjusting the lengths of both of segments, and in said unlinked mode movement of a transition results in the length of one of said segments being modified while its adjoining segment retains its original segment length.

12. A computer readable medium according to claim 11, wherein said computer-executable instructions include additional instructions for performing the step of storing each segment with data including a segment start time and a segment end time.

13. A computer readable medium according to claim 12, wherein said computer-executable instructions include additional instructions for updating two data blocks when operating in said linked mode or updating one data block when operating in said unlinked mode.

14. A computer readable medium according to claim 11, wherein said computer-executable instructions include additional instructions for converting movement data into representations of timecode.

15. A computer readable medium according to claim 11, wherein said computer-executable instructions include additional instructions for changing an attribute of a displayed icon in dependence upon a selected mode of operation.

16. In a computer system having a graphical user interface including a display and a user interface selection device, a method of performing editing operations upon image frames, comprising steps of displaying image frames in response to stored segment data; displaying visual elements representing adjoining image segments in response to said segment data; selecting and adjusting transitions between adjoining image segments by operation of said user interface device such that segment data is modifiable in response to said adjustments; and selectively operating in a linked mode or in an unlinked mode, such that in said linked mode movement of a displayed transition between adjoining segments maintained said segments as being adjoining by adjusting the lengths of both of said segments, and in said unlinked mode movement of a displayed transition results in the length of one of said segments being modified while its adjoining segment retains its original segment length.

17. A method according to claim 16, wherein an attribute of a displayed icon is changed in dependence upon a selected mode of operation.

18. Apparatus for editing image data substantially as herein described with reference to the accompanying drawings.

19. A method of editing image data substantially as herein described with reference to the accompanying drawings.