F.S vs M.C vs C.K
F.s=Flash-selection, M.c=Motion
control, C.k=chroma key
E1. With the non
existence of any other technique than a chroma key or motion control ( as far as I could my guess), for cine-, video or photo
image-editing, the flash selection is, the third alternative one, that is devised by me.
E2.Both these earlier ones,-…the Chroma-key and the Motion-Control are practiced, for the special effect sequences
in Holly wood cinema and others. They are good at for the purpose of selection
only, and not any other added features than what are concerned with. Asked me
of, what else could be anticipated from a tool meant for purpose of selection only.
But it will be learned in the proceeding pages of my web site, describing of how, the Flash-Selection has in itself in-built with a multitude of other features, apart from, of course the capability
of selection.
E3. My effort is to implement certain kind of logics and infusing intelligence, on subject relating to photography, motion
picture special effects and Image editing. Blue screen process, motion control
are the other two such techniques already being implemented in motion picture to achieve special effects.
What is Blue screen (Chroma Key) Process:
E4. As said earlier, the software of a computer, with the required
set of instruction (logics). It could do a task like for e.g., to search and
locate areas in an image, consisting of a defined color, say a blue, green or pink.
This factual could be applied to distinguish or to mark an outline, around an object or element that is surrounded
by a background of uniform colour & contrast. In the earlier motion-picture
of pre – digital era, a bright blue color background was used for that purpose, on which the actor performs. The Color-separation
was done optically, capitalising on film with blue sensitivity, hence called Blue–screen process. But a present day any color could be treated as a background as long as, that specific color should not
be present in main subject. Since we are to the effect to identify any one color that is defined, hence is called as chromakey – a process of Keying-in.
Motion control technique:
E5. The procedure mentioned in chromakey involves to search for how many pixels (the smallest fraction, that a picture could be broken down into)
of identical color, that a single imagemay consist of. But to anticipate a background of such a color of uniformity in the
natural world would be a most absurd idea, unless shooting in the sky or in the mid-sea is the location voluntarily desired
for adventure. Luckily there is an alternate way to execute selection of pixels of similarity. That is by comparing two pictures
that comprises of identical image content, except for a few elements that has been removed (deleted), or displaced in its
orientation. The power of computing could then, define areas where changes
has occurred.
E6. Explained in the following passage, how such logic is executed in a technique called motion–control. The motion control, could at-best, a theoretically perfect technique for selection, where in a world of
nil dynamism (stand still), except disregarding the events of movements of the
performing Actor... The liberty for him to wander around. The process, involves
much more complexity, in its implementation, at the shooting stage.
E7. Firstly a remotely operable movie camera is mounted on a crane like robotic arm called, a 'Jig'. The whole set up
is capable of repeating all the action of camera-maneuvers done on the previous take, such as focusing, zooming, panning or
tracking, with the precise controlling power of a computer. The First execution of a take is, picturing the performance of
an actor, at the natural outdoor or in a controlled studio set. Then the corresponding Take of a shoot is shot once again. This subsequent shot of a take be called as the reference or ref-take (in short) for
easy understanding.. The subsequent one of ref-take is done, but this time with out the actor; hence capturing only the background
scenery. Each frame-by-frame is compared in parallel, between the Key frames
of main take and its relevant frames
of ref: take,(reference) for similarity, to derive the selection as explained
earlier
Flash-selection technique
E8. flash selection –it deem to be
come a photographic practice a new technology in itself which basically involves with making two exposures of frames taken
with different apertures at fixed shutter speed of shutter or with a constant aperture setting but varying shutter speed.
E9. This technique carries out a selection methodology, by comparing two frames of images
of same subject except that a density variation has occurred due to an instant change in the pattern of lighting between those two images. These images are as a result
of exposure on two separate frames, which are exposed in a succession but (i.e.,
One frame after another), and a dedicated software to analyze the variation.
E1.
. In a varying aperture mode for the first frame ( we may refer it as key
frame) the ambient light is made use of, where the measured exposure level may leads to determine an exposure at a nominal
1/60th.sec @ f:11 suggestive of a bright sunny day. The adjacent frame is made to receive an exposure of 1/1000th.sec @ f:2.8 if the is not practical(when such a wide aperture is not provided on the
lens or availability of ambient lighting is not high enough)....hence one could opt for, 1/500th.sec @ f:4 for the second exposure the light from a flash (thrown at from camera position) in addition to ambient light, is utilized.
E2. Earlier the technique was explained with a story , but That was too much
of a Monkey Business. Let’s get back to the Main–stream topic, but technically.
– the
technique of flash selection.s
E3. We know in motion control, there is involved, locating all the identical pixels between key frames and reference frame.
For such a requisite, uniformity of lighting is also maintained (kept constant) between both the takes, apart from the criterion's
earlier mentioned.
Flash -selection How
The procedural aspects & ingredients required for the technique
I repeat...
E4. a) This technique carries out a selection methodology, by comparing
two frames of images of same subject except that a density variation has occurred due to an instant change in the pattern
of lighting between those two images. These
images are as a result of exposure on two separate frames, which are exposed in a
succession (i.e., One frame after another), and a dedicated software to
analyze the variation.
E5. b) Inherently A source of
lighting is required that could complete even the adverse condition of high intensity, and along with higher-contrast that the sunlight would provide naturally . When non
of the man made lights could be compared for its intensity of sun that shines upon us, the only probable means to counter this is resorting to a flash at high synchronization.
It invariably, means a new kind of shutter is required with such a sync facility @ higher shutter speed.
E6... But in contrary in motion control, in a flash selection, an additional
lighting of brief duration (spurt) a flashing effect, derived from a flash, like
of a conventional photo-flash, tungsten or from a Day light is thrown at the subject, while the main take is in progress. In the image it is recorded The lighting
of flash, that was in a feeble flickering
(designated as ref: lighting), almost
not discernible at the shoot, but disturbs the lighting pattern of the intended lighting (the primary lighting) planned
for a shoot. The intervening disturbance by the ref: lighting would give-rise to ref-frames, at a regular interval of 4 or
6 or 8 frames apart, among a series of key frames of the main take, (that has used only the primary light).
E7...The intention here is to analyze, (a). For similarity (b).where and how much a variation has occurred, in comparison
between, those of key and ref: frames--- derived from the primary and ref: lighting
respectively.
. But there arises a new kind of requisite with flash-selection.
E8. The need to employ a lighting, powerful enough to compete with the ambiance of Primary lighting (the lighting actually
been employed for the shoot). In many situations, we should make ourself in a
preparedness, to challenge the primary lighting of natural Daylight, which would have a high-intensity of light combined with
lighting- contrast in it's extreme case. Fortunately a normal flash light used
for photography (little modified), synchronized at a very high shutter-speed, could meet with such a task. The highest sync
speed available in photography is around 1/250th of a second. But the sync speed we are concerned here, in the region of 1/1000th
second or beyond. Any way It may not be a deterrent to carryout the process of flash selection, The following ones, could
be resorted, as other options.
a). The Latest
camera has this high sync option (called with different names), such as Auto FP high-sync a functionality, to synchronize
at high shutter combined with dedicated flash-
guns of their own Brand
b). I would be able to suggest
a design for a new type of shutter, be custom -Made.
c). The R&D facilities
of the Camera-Companies in the future could able to workout for yet another type of shutter.
d) As an alternative way, where in instead of lighting is being added, conversely it could also be deducted, for ref:take.
e). Perhaps many a times, the adverse photographic condition may not be or always be at severe and may not be the case
to be faced with probably in an European country. In such case, a slow speed of shutter and, the other lighting sources could
be resorted to (as long as the light dispersion is divergent in character).
f).Choosing a more powerful flash or an alternative source
of light, thereby a slow sync could be used.
g). Space reserved for other tricks by me, or the ones you could suggest one. .
Please note:
The information /guidance provided and my suggestions as above or from any of
my web page, of similar content published in my other web-sites are prohibited for commercial
usage or for publication purpose ,without the consent of the ,author s.kalaivanan the proponent of the idea/ concept
