2. BITS DEPTH
• Every color pixel in a digital image is created
through some combination of the three
primary colors: red, green, and blue.
• Each primary color is often referred to as a
"color channel" and can have any range of
intensity values specified by its bit depth.
3. BITS DEPTH
• The bit depth for each primary color is termed
the "bits per channel." The "bits per pixel" (bpp)
refers to the sum of the bits in all three color
channels and represents the total colors available
at each pixel.
• Confusion arises frequently with color images
because it may be unclear whether a posted
number refers to the bits per pixel or bits per
channel. Using "bpp" as a suffix helps distinguish
these two terms.
4. BIT DEPTH
• Bits Per Pixel Number of Colors Available Common Name (s)
• 1 2 Monochrome
• 2 4 CGA
• 4 16 EGA
• 8 256 VGA
• 16 65536 XGA, High Color
• 24 16777216 SVGA, True Color
• 32 16777216 + Transparency
• 48 281 Trillion
5. BIT DEPTH
• The human eye can only discern about 10
million different colors, so saving an image in
any more than 24 bpp is excessive if the only
intended purpose is for viewing.
• On the other hand, images with more than 24
bpp are still quite useful since they hold up
better under post-processing.
6. What is H.264/AVC?
• H.264/Advanced Video Coding (AVC) is an
industry standard for video compression. The
H.264 standard is also known as MPEG-4 part
10 and is a successor to earlier standards such
as MPEG -2 and MPEG -4.
7. What is H.264/AVC?
• H.264 delivers MPEG – 4 quality with frame
size up to four times greater. It can also
provide MPEG -2 quality at reduced data rate,
requiring as little as one third the original
bandwidths.
8. APPLE ProRes4:2:2:(4)
• Apple ProRes 422(HQ)
•
• This codec supports full-width, 4:2:2 video
sources at 10 –bit pixel depths, while retaining its
visually lossless characteristic through many
generations of decoding and re-coding.
•
• 10-bit images can carry finer gradations of colour,
thereby avoiding the banding artefacts that can
occur in 8-bit images.
10. AVID DNxHD
• Avid DNxHD, which stands for "Digital
Nonlinear Extensible High Definition", is a
lossyhigh-definition videopost-
productioncodec engineered for multi-
generation compositing with reduced storage
and bandwidth requirements.
11. AVID DNxHD
• DNxHD is a video codec intended to be usable
as both an intermediate format suitable for
use while editing and as a presentation
format.
• DNxHD offers a choice of three user-selectable
bit rates: 220 Mbit/s with a bit depth of 10 or
8 bits, and 145 or 36 Mbit/s with a bit depth
of 8 bits.
12. 2K Vs 4K
• The terms 2K and 4k originally referred to output of a
film scanner. Each frame of 35mm film scanned gave
you 4,000 red pixels, 4,000 green pixels, and 4,000 blue
pixels in other word, 4K all round.
• The high -end HD camera (true 4K0 have the same
relationship on a full frame sensor, providing 4,096
photo sites (pixels) in an imagining area of 35mm film.
This means you have 4,096 red, 4,096 green, and 4,096
blue photo sites captured, which is commonly referred
to as 4:4:4.
13. 2K Vs 4K
•
• “If aspect ratio of a full 35mm film frame is
4x3 and you have 4,096 photo sites across the
width and 3,000 along the height, then you
have basically 4K by 3K. That’s 12 million of
each of the green, red, and blue photo sites,
or 36 million photo sites. That equates to
what you’d get with a 4K film scan – a 36
megapixel scan.”
14. 2K Vs 4K
• “ 4K doesn’t mean that just because you have
4,096 green photo sites and 2,048 red and blue
that get interpolated through software, it’s a true
4K camera!
• You can’t take an 8.3 million photo site sensor
and create 36 million pixels out of that without
interpolation and claim to have a 4K camera.”
•
15. 2K Vs 4K
• Making such claims is often referred to as
marketing pixels. Mr Erland points out that
RED isn’t the numbers with a similar
technique and rely heavily on pushing the
megapixels.
• Not all 4K cameras in the market are truly 4K.
Red One – its amazingly flexible and
customisable camera, but it lacks the truth
behind its 4K capabilities.
16. Dynamic Range
• Dynamic Range is total range of tonal values
recordable or usable. It’s noise tolerance
dependant, but not scene dependent.
•
17. Dynamic Range
• How do we measure Dynamic Range?
• Film a chart under controlled conditions – EV
steps/fstops
• Measure the pixel noise (RGBY)
• Check the Dynamic response
• Map the noise in fstop(EV) in each of RGB
• Map the log of the exposure for each RGB
•
• EV=
18. Exposure Latitude
• Exposure Latitude is by how much you can
over and under expose and still have a usable
image. It’s scene dependant.
19. REC 709
• Is the output format for traditional television
workflow. “Rec 709’ is short for the
International Telecommunication Union’s ITU-
R Recommendation BT.709. Rec 709 is the
international standard for displaying images
on video monitors, Look Up Tables (LuTs) are
not necessary to show these images on
monitors or to create dailies or editing
proxies.
20. REC 709
• Rec 709 images can be easily processed by
most HD video post production gear in real
time. While providing somewhat reduced
choices in colour grading.
21. DCI P3
• Is suited for DCI P3 (also known as SMPTE 431-
2) compliant displays. Those are primarily
digital cinema projectors, but an increasing
number of LCD displays support DCI P3 as
well. DCI P3 has a similar tone mapping to REC
709 but a wider colour gamut that is designed
to approximate the colour gamut of print film.
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