Increased depth of field for photography
OwnerKjell Olssoninventor
Life of this patent
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Abstract
The invention comprises a method and system for achieving increased depth of focus at photography. The method creates an improvement of depth of field at use of traditional “Tilt and Shift” - technique, and increased possibilities to obtain good depth of field with other and quite ordinary cameras. The method is primarily meant for electronic cameras, where the image is created electronically from a sensor in the camera and is based on a multi photo technique. Several photos are shot with different focused parts of the scene subjects in respective photo, and a basic image is integrated by contributions from the different images. Calculated image transfers based on lens- or sensor settings for respective image, compose a starting point for corrections of images and selection of respective image contributions.
Claims18
A method to increase the depth of focus, giving improved sharpness of subjects with such extensions that sharpness regularly cannot be obtained over the whole picture, using at least two images obtained with different camera settings, which include at least one of change of focus and change of aperture, in mainly keeping the same position of the lens optical center relative to the subject, and combining information from those images to obtain one new image, the method comprising the following steps:
- a. taking photos of subjects with different focus settings between images, creating different focus for different image areas, including natural variations and disturbances of the photo sequence, generating changes in the images exceeding the said change of focus, the changes in images composing changes including any of position, scale and perspective;
- b. matching the different photo-images to the position, scale and perspective of a selected basic image comprising the sub-steps of
- b1. selecting a basic image;
- b2. identifying and localizing border lines and highly contrasting structures in a number of images;
- b3. calculating the geometrical transfer of a number of images to the basic image, using at least one of position shifts, change of scale and perspective tilting;
- b4. choosing common references for evaluating and/or correcting the matching of the images using the positions of identified common structures;
- c. building a new image from the matched images by sub-steps including
- c1. analyzing image areas with continuous change of focus of image elements in the area, corresponding to a continuous change of distance, where focus changes are utilized for borderlines and/or highly contrasting structures in distance, and
- identifying transfer positions, where change of focus is of corresponding size seen from the respective image focused state, and
- selection of a transfer border between image information from one image and next neighboring focused image, considering the said transfer positions, and
- when large discontinuities in the image transfer are present, a fine tuned match is performed of the two images along the common transfer border, including any method step from (b);
- c2. selecting border lines for analyzing a number of border line areas, regarding differences in focus between the two sides of the border line for the respective focused image, for identifying transfer borders with focus distance gaps larger than a given value;
- correcting the border line area, where the border line is a transfer border according to (c2), between different focused images, with reduction of defocused image information from the defocused image side to the focused image side, and when the said focus gap is less than the said given value, the transfer is considered as the transfer according to (c1);
- c3. utilizing, for the analysis of focus in (c1) and (c2) fast variations of light and/or color as functions of area based space coordinates, comparisons for best focused state between images, using borderlines and/or highly contrasting structures of subjects,
- d. merging the identified focused image regions, according to (a)-(c), into the said one new image.
Dependencies are inferred from the claim text.