METHOD AND CAMERA FOR PRODUCING DYNAMIC PROOFS FIELD OF THE INVENTION The present invention relates to a method for processing images captured using a digital camera in order to produce a dynamic proof with lenticular grid. The invention has applications for all types of digital photographic camera but also for other equipment integrating a camera function and possibly communication functions. The invention applies in particular to phonecams. BRACKGROUND OF THE INVENTION The transfer of camera images onto lenticular grid media is a known technique. Several images are interlaced and linked to a lens grid so that the individual images appear successively to the observer when he/she varies the angle of observation of the medium. The image sequence that the observer thus makes appear has a dynamic character. A zoom type effect may be simulated, h this matter one can refer to the document (1) whose reference is given at the end of the description. The image sequence can be, for example, a video clip. Various transfer methods of an image sequence onto a lenticular grid medium are known, hi particular one may refer to the documents (2), (3), (4) and (5) that provide an illustration of this. The full references of these documents are also given at the end of the description. The various known methods and devices for image transfer onto a lenticular grid medium have as a common point the fact that they require considerable intervention by the user to select the images to be transferred and assemble a sequence. The devices used for the transfer have large size control and viewing interfaces for this purpose. The user of more summary devices, such as cameras or image capturing phones, do not generally have a sophisticated control interface or comfortable viewing screen. Thus, this user is dissuaded from lenticular grid media. Assembling a sequence indeed proves to be tricky using pocket equipment. In addition, a higher price of lenticular media, by comparison with conventional
photographic paper, discourages the user from making a print whose result is unpredictable. SUMMARY OF THE INVENTION It is the object of the invention to propose a processing method of images for the production of lenticular grid proofs, not having the above- mentioned difficulties. To achieve these objects, the invention more precisely relates to an image processing method comprising, following the capture of one or more images using a digital camera with an integral control screen, the following steps: a) the automatic establishment of an image sequence from the image data of said captured image, b) the dynamic display of the image sequence on the control screen, and, in response to a user control, c) the transmission of image data relative to the sequence, to production equipment of lenticular grid dynamic proofs, so as to produce a lenticular grid proof reproducing the sequence previously displayed on the control screen. The method can be completed by a dynamic proofs fabrication step and by their transmission to the user. Dynamic proof means the result of the transfer of the images of the sequence onto a lenticular grid medium. This medium can be, for example, in the form of flat card. Thanks to the invention method, the image sequence is established automatically. Thus, the user's intervention can be limited to the simple choice of whether to transfer or not the sequence onto a lenticular grid medium. Further, the dynamic display of the sequence on the camera's control screen enables the modification of the observation angle of a lenticular grid to be simulated. The display thus lets the user have an accurate idea of the result of the transfer onto a lenticular grid medium, despite the small screen size. The transmission of image data relative to the sequence can take place immediately in response to the user's control, if his/her equipment allows suitable data transmission. It can thus take place via a Hertzian channel and/or via
a communication network. The data can also be saved and transmitted later, for example when the user gets to a proof fabrication terminal ("kiosk"). The method can be implemented based on many captured images, for example, a series of images corresponding to a video clip. It can also be implemented based on a single captured image. The method thus enables a particularly flattering presentation of the image contents. Step b) of the method, i.e. the automatic establishment of a sequence, can comprise various operations among which are operations of defining interest zones, scanning, zooming and reframing. Intermediate images, movement fade, cross fade, morphing, or other effects of warping and more generally any effect of transition between images can be generated before the transmission of the image data, for example, during the establishment of the sequence. When the sequence is made up from a single captured image, step b can more precisely comprise: - the automatic identification in the captured image of at least one interest zone, - for each interest zone identified, the automatic selection of an image portion containing the interest zone, and - the formation of an image sequence comprising selected image portions. The transmission of image data relating to the sequence can comprise the transmission of all the data of each of the images making up the sequence. However, when the sequence is made up of a single captured image, the data transmission can also comprise the transmission of the single captured image data, the transmission of data defining the zones of this image as well as the parameters of transition between the zones and the duration and number of intermediate images. The zones correspond, for example, to the above-mentioned selected image portions that surround the interest zones. Each zone can be defined, for example by four points that correspond to the nodes of a rectangle outlining the zone.
The invention also relates to a digital camera designed to implement the above-mentioned method. The camera comprises a display unit and a central processing unit programmed to implement the method. It also has a control for selection between static proofs, i.e. conventional photographic proofs, and dynamic proofs on lenticular grid media. Other characteristics and advantages of the invention will appear in the following description, with reference to the figures in the appended drawings. This description is given purely as an illustration and is not limiting. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a flowchart showing the implementation of an image processing method according to the invention. Figure 2 shows a step of the method corresponding to the automatic establishment of an image sequence from a single captured image. DETAILED DESCRIPTION OF THE INVENTION Identical or similar parts of the various figures use the same references. Reference 10 designates a shot during which one or more images are captured. The shot can be taken using a digital camera 12 shown summarily. It is provided, in the example shown, with a data storage memory 14, a central processing unit 16, a selection control of proof type 17 and a control of shooting type 18. ' The shooting type control 18 enables in particular the selection of an image-by-image shooting mode, in which a single image is captured at each release, and a "video" shooting mode. hen video mode is selected a clip of several images is captured. The camera generates the image data used in a following step 20 to automatically establish an image sequence. The images that make up the sequence are automatically generated based on the image data of the captured images. The following description refers more precisely to the case when an image sequence is generated based on a single captured image. The sequence can nevertheless
incorporate the data of several images, and especially several images of a video clip. The images of the sequence can comprise portions of the captured image, the entire captured image, portions of the captured image that have undergone transformations, and possibly additional images not coming from the shot. The sequence is generated automatically and requires no specific user control. However, it can be envisaged that the user may enter controls relating to a processing or to wanted special effects. The input of additional data, which is not necessary to implement the method, is shown by a broken line with reference 22. More precise aspects of the establishment of the sequence are described with reference to figure 2. The image sequence can be established in the central processing unit 16 built into the camera. The central processing unit can also be a remote unit. In this case, data transmission means, by Hertzian or optical channel, or by network, link the central processing unit to the camera. The image sequence established by the central processing unit can in particular be in the form of a data set 24, for example a set of digital files that each contain the data of an image of the sequence. An ordered succession of the files can correspond to the images of the sequence. While the initial image can constitute one of the sequence images, remember that the sequence images are essentially generated based on the data of the captured image and are different than the latter. The sequence can also be in the form of a single image data file 26, to which the selection data 28 are added. These data can be part of the file itself when descriptive language of the x l type is utilized. These define among the file data 26 those constituting the data of each image of the sequence. The selection data define, for example, portions of the captured image, enlargement ratios of these portions, a display order of the various portions, etc. A following step of the method, indicated with reference 30, corresponds to the display of the previously established sequence. This step is important, because it lets the user see, on a control screen 15 of the camera, the
result capable of being obtained by the transfer of the image sequence onto a lenticular grid medium. After having viewed the sequence, the user can make a choice indicated with reference 40. A first possibility 41 of this choice can be to reject the automatically established sequence. A second possibility 42 can be to cause the establishment of a new sequence. This possibility is indicated by an arrow 42 with broken line that returns to the start of step 20 establishing the sequence. For this purpose the camera's central processing unit can be programmed to prepare, with each return of the user, a slightly different sequence, by using other selection or establishing criteria for the images of the sequence. A third possibility 43 is to order a proof corresponding to the captured image or images. Another choice 50 is presented to the user. Indeed he/she can choose between a conventional proof of the captured image, or a dynamic proof, on a lenticular grid medium. The latter then reproduces the previously established and viewed sequence. The second choice 50 and the first choice 40 are separated on the figure for clarity purposes, but can be made from the same control, whether simultaneously or not. For example, this refers to the previously mentioned selection control 17. Reference 60 designates a subsequent step of data transmission 24, 26, 28, relating to the sequence images, to a service provider or equipment capable of producing the lenticular grid dynamic proof 62, and possibly the conventional proof 64, wanted by the user. By extension step 60 includes the production of proofs 62, 64 and their routing to an addressee chosen by the user or to the user themself. Production of the proofs can in particular take place in a photo kiosk or digital terminal integrating appropriate printing means and a unit for data exchange with the user's camera equipment. The data exchange can be an exchange by proximity communication, of Bluetooth type, for example, or an exchange by means of a telecommunications network. It can also take place by means of a data medium. Figure 2 shows a special automatic method for establishing the image sequence. A first step of this method can comprise the automatic
identification of interest zones 74 in a captured image 70. Interest zone means an interest zone of the image capable of holding an observer's attention. These are for example zones representing faces. The identification of image zones representing faces involves a known technique. It simply consists in searching in the images for colors that correspond to the color ranges predefined as corresponding to a skin color. Other criteria of shapes or geometries are then applied to the selected color zones enabling the presence or not of a face to be confirmed. Other criteria for the automatic identification of interest zones can also be selected either additionally or alternatively. For example, the identification step of interest zones can comprise the automatic identification of image zones 75 representing more or less unified color areas, hi this case, zones in addition to the zones representing more or less unified color areas are selected as interest zones. Such an identification method more generally enables the selection of image zones that are not patches of sky, grass or ground. It can be implemented, for example, when no zone corresponding to skin colors is identified. The relative size of the unified areas to be avoided can be pre-set. Other criteria, such as the existence of zones of strong contrast of light, color and texture, zones with edge connection or a particular size and also combinations of these criteria can also be selected for the automatic identification of interest zones. A frame A, B, C, D, of fixed or variable size according to the dimension of the identified zone, can be used each time to define an image portion 72 to be selected for forming the sequence. The frame can be summarized by the simple point or pixel coordinates that outline an image portion. It can be centered on the identified interest zone, or at least surround this zone. For an especially user-friendly viewing of the image sequence, the method can also comprise the automatic selection of additional image portions 76, not necessarily containing interest zones, but located on a path 78 linking two selected image portions and containing interest zones. They are represented on figure 2 with broken lines. The insertion of these image portions into the image sequence enables fluid panning to be obtained between the image portions
containing an interest zone. Such panning involves a known technique. In this matter one can refer to the document (6) whose references are set out at the end of the description. The number and position of the additional images inserted for panning can be variable. It is for example adjusted to the number of automatically selected image portions that contain an interest zone. The number of images of the sequence, whether or not containing an interest zone, is moreover adjusted not to exceed a maximum number of sequence images capable of being transferred onto the same lenticular grid medium. The panning path 78 used can be variable. For example, the path can be the shortest straight line linking the two nearest image portions, containing an interest zone. The path can also be a smoothed curve path, as shown in figure 2. The selection of the sequence images then amounts, in the illustrated example, to retaining an ordered assembly of digital data sets 24, 24i. These are the data set previously mentioned with reference to figure 1. The index i is used here to designate the data sets relating to the intermediate images, without interest zone, simply used for the fluidity of the dynamic representation. As an alternative, data indicating the position and dimension of the frames can also be established. These are, for example the coordinates of the nodes A, B, C, D of each frame. These data correspond to the data indicated by reference 28 in figure 1. Several successive images of the sequence can also refer to the same interest zone, by defining the images or frames that close around the interest zone with an increasing enlargement ratio of the relevant portion of the initially captured image. This results in a zoom effect. The intermediate images are not necessarily portions of the initial image located on a panning path. They can also be calculated in all parts from two or more selected successive images of the sequence, so as to generate cross fade, morphing or other effects. Reference documents (1) US 6 366 407 (2) US 6 177 217
(3) US 6 320 669
(4) US 6 198 544
(5) US (2003/01 28287)
(6) US 6 362 850