Introduction to Digital Photography

1
Introduction toDigital Photography

• Glossary, Definitions, and Digital Concepts
• Instructor David King

2
Digital
Photography Glossary, Definitions, and Concepts
Digital Still Photography was developed from
Video Electronic Capture

• The first Still Cameras Captured an NTSC Video
  Frame
• An NTSC Video frame is 1/30 of a second. (NTSC
  Video plays at 30 frames per second.)
• A FRAME is made up of two interlaced FIELDS
  to create the full image. Each field is 1/60 of
  a second.
• Each field contains every other line of pixels
  on a screen.
• There are about 500 lines per screen in normal
  NTSC Video. Filtering can raise this to
  about 530. It is approximately equivalent to
  a 640 x 480 pixel image at 72 pixels per inch.
  (Hi Def is approximately double that
  resolution).

Instructor David King

dking_at_sdccd.edu
3
Digital
Photography Glossary, Definitions, and Concepts
Digital Still Photography was developed from
Video Electronic Capture

• One of the first viable cameras was the Sony
  Mavica which used 1.44 megapixel/3.25 inch
  floppy discs to store its video-based images.

Instructor David King

dking_at_sdccd.edu
4
Digital
Photography Glossary, Definitions, and Concepts
Capturing an Electronic Image

• The image is captured with an imaging chip or
  sensor that converts light energy into an
  electrons that can be measured based on
  intensity.
• There are two technologies in use to make photo
  imaging chips.

CCD Charge-Coupled Device CMOS
Complimentary Metal Oxide Semiconductor
Instructor David King

dking_at_sdccd.edu
5
Digital
Photography Glossary, Definitions, and Concepts
Capturing an Electronic Image

• Is one technology better than the other?

CCD Charge-Coupled Device Initially
less costly to manufacture More uniform readings
since data goes through fewer readers Less
heat therefore less inherent signal
noise Requires additional processing chips in
system and high power use CMOS Complimentary
Metal Oxide Semiconductor Each pixel had its
own reader More circuits on chip making for less
system complexity Less power consumption and
greater battery life Higher speed
Instructor David King

dking_at_sdccd.edu
6
Digital
Photography Glossary, Definitions, and Concepts
Capturing an Electronic Image

• Defining an Image chip of either type
• A CCD or CMOS imaging Chip has Four major
  characteristics. (This is the digital equivalent
  to film types and formats.)

1. PHYSICAL DIMENSION/SIZE That is, how big is
the chip? Size is usually measured in
millimeters (mm) or expressed in a label. Full
Frame 36mm x 24mm (Size of 35mm film
image) APS/DX 23mm x17mm 22mm
x15mm 4/3 18mm x 13.5
(Olympus Only) Point and Shoot chips can
range from 8mm x 6mm and down Digital
Backs (MF) are from 36mm x 36mm to 48mm x 48mm
and up Scanning Backs (LF) are from 125mm
x 100mm and up.
Instructor David King

dking_at_sdccd.edu
7
Digital
Photography Glossary, Definitions, and Concepts
Capturing an Electronic Image

• Defining an Image chip of either type
• A CCD or CMOS imaging Chip has Four major
  characteristics

2. ASPECT RATIO That is, what SHAPE is the
chip? Full Frame and APS/DX 32
like a 35mm camera 4/3 and most PS (and
Video) 43 which is more like an 8x10 print
Square many Digital Backs produce a square
image
Instructor David King

dking_at_sdccd.edu
8
Digital
Photography Glossary, Definitions, and Concepts
Capturing an Electronic Image

• Defining an Image chip of either type
• A CCD or CMOS imaging Chip has Four major
  characteristics

3. PIXEL DIMENSION That is, how many photo
sites are on the chip? Dimension is
measured in Megapixels (Millions of
pixels) DSLRs Currently 6 Mp
to 16.7 Mp MF Backs Currently 11 Mp
to about 40 Mp LF Backs 80 to over 120
Mp Point Shoot Currently 3 to 10 Mp
Instructor David King

dking_at_sdccd.edu
9
Digital
Photography Glossary, Definitions, and Concepts
Capturing an Electronic Image

• Defining an Image chip of either type
• A CCD or CMOS imaging Chip has Four major
  characteristics

4. PIXEL SIZE/DENSITY That is, how big is each
photo site and how close are they to one
another?
Instructor David King

dking_at_sdccd.edu
10
Digital
Photography Glossary, Definitions, and Concepts
Capturing an Electronic Image

• Other Major Camera/Back differences to consider

FRAME RATE for CONTINUOUS SHOOTING That is, how
fast can you take one shot right after
another? IMAGE BUFFER That is, how many images
can be stored in the system buffer before it has
to pause to empty onto the memory card? BUILD
DURABILTY Composite, plastic, metal and how is
it sealed against weather and the
elements? ERONOMICS How easy is it to hold and
shoot? How quickly can you get it into action or
find all of the controls and buttons? LENS
AVAILABILITY What lenses and of what quality
are available? In the end, picture quality is
all about the GLASS!
Instructor David King

dking_at_sdccd.edu
11
Digital
Photography Glossary, Definitions, and Concepts
Capturing an Electronic Image

• Why is the lens so important?
• We need to see how a chip differs from film in
  how it records an image

Instructor David King

dking_at_sdccd.edu
12
Digital
Photography Glossary, Definitions, and Concepts
Capturing an Electronic Image

• Why is the lens so important?

Instructor David King

dking_at_sdccd.edu
13
Digital
Photography Glossary, Definitions, and Concepts
Capturing an Electronic Image

• Why is the lens so important?

Instructor David King

dking_at_sdccd.edu
14
Digital
Photography Glossary, Definitions, and Concepts
Capturing an Electronic Image

• Why is the lens so important?

Instructor David King

dking_at_sdccd.edu
15
Digital
Photography Glossary, Definitions, and Concepts
Capturing an Electronic Image

• Why is the lens so important?

Instructor David King

dking_at_sdccd.edu
16
Digital
Photography Glossary, Definitions, and Concepts
Capturing an Electronic Image

• Why is the lens so important?

Instructor David King

dking_at_sdccd.edu
17
Digital
Photography Glossary, Definitions, and Concepts
Capturing an Electronic Image

• Different cameras have different approaches to
  these issues. So Which is best? Or What are
  the trade offs?

IT ALL DEPENDS ON WHAT YOU ARE SHOOTING
JUST LIKE WITH FILM!!! Well address these
issues in detail as the class goes on
Instructor David King

dking_at_sdccd.edu
18
Digital
Photography Glossary, Definitions, and Concepts
Resolution versus Resolution

• A Few different kinds of resolution

In Film we had Grain A result of film speed
and format size (Grain enlarged as the print was
enlarged) In Digital we have PPI Pixels
Per Inch (File resolution) (Does not change with
enlargement) DPI Dots Per Inch (Printer
ink resolution) LPI Lines Per Inch (Offset
reproduction resolution) LPMM Line Pairs
Per Millimeter (Lens resolution)
Instructor David King

dking_at_sdccd.edu
19
Digital
Photography Glossary, Definitions, and Concepts
Resolution versus Resolution

• Pixel density and a files pixels per Inch
  would seem to determine how fine can be the
  detail recorded in a file, But it is just the
  start then there is interpolation

Interpolation is calculating what goes between
other known data. Extrapolation is calculating
what lies outside the known data. Because a
photo site only registers luminosity (the
intensity of the light striking it)
interpolation is the process by which the digital
cameras Processor determines color. But it has
a major effect on resolution.
Instructor David King

dking_at_sdccd.edu
20
Digital
Photography Glossary, Definitions, and Concepts
Resolution versus Resolution The BAYER Filter
/ Pattern

• Different processors interpolate differently but
  for this hypothetical 12x8 (96 pixel) chip, here
  is one way

Instructor David King

dking_at_sdccd.edu
21
Digital
Photography Glossary, Definitions, and Concepts
Resolution versus Resolution The BAYER Filter
/ Pattern

• Grid is divided into 4-block primary squares.

Instructor David King

dking_at_sdccd.edu
22
Digital
Photography Glossary, Definitions, and Concepts
Resolution versus Resolution The BAYER Filter
/ Pattern

• The luminosity under each filter is measured and
  assigned. Then the next block is processed until
  all are completed.

Instructor David King

dking_at_sdccd.edu
23
Digital
Photography Glossary, Definitions, and Concepts
Resolution versus Resolution The BAYER Filter
/ Pattern

• A primary pixel is assigned the resulting RGB
  value. Then the next primary pixel.
  Intermediate pixels discard the initial reading.

Instructor David King

dking_at_sdccd.edu
24
Digital
Photography Glossary, Definitions, and Concepts
Resolution versus Resolution The BAYER Filter
/ Pattern

• Based on the primary pixels, the in-between
  pixels are interpolated.

Instructor David King

dking_at_sdccd.edu
25
Digital
Photography Glossary, Definitions, and Concepts
Resolution versus Resolution The BAYER Filter
/ Pattern

• The averaged primary and interpolated in-between
  values are then sent to the memory card.

Instructor David King

dking_at_sdccd.edu
26
Digital
Photography Glossary, Definitions, and Concepts
Resolution versus Resolution Other approaches
FUJI

• Fuji arranges their photo sites in a diamond
  pattern to increase horizontal resolution
• then puts two sensors at each site a large and
  small sensor to increase the dynamic range.

Instructor David King

dking_at_sdccd.edu
27
Digital
Photography Glossary, Definitions, and Concepts
Resolution versus Resolution Other approaches
SIGMA / FOVEON

• Foveon was a pioneer of the non-video approach
  to image sensing and produced one of the very
  first functioning digital cameras a Compac
  laptop with a Canon lens mount.
• The Foveon chip used in the Sigma cameras uses
  three stacked RGB filters at each photosite to
  eliminate interpolation.
• They claim this gives them a 3X increase in
  resolution over the actual pixel dimension of the
  chip.

Instructor David King

dking_at_sdccd.edu
28
Digital
Photography Glossary, Definitions, and Concepts
The Inevitable Comparisons with Film So
what are you giving up to switch or go to
Digital? The normal comparisons involve
these image factors

• Dynamic Range
• Color Range
• Detail
• Tonalities
• Image Durability
• Cost and Time

Instructor David King

dking_at_sdccd.edu
29
Digital
Photography Glossary, Definitions, and Concepts
The Inevitable Comparisons with Film DYNAMIC
RANGE
This is the range of tones that can be recorded
from deep black shadows to bright white
highlights. It can be expressed ?
in terms of stops of exposure, or
? in terms of a Density / Gamma range as measured
on a densitometer.
Instructor David King

dking_at_sdccd.edu
30
Digital
Photography Glossary, Definitions, and Concepts
The Inevitable Comparisons with Film DYNAMIC
RANGE
MEDIA STOPS GAMMA Film Color Pos.
11 2.8/- Film BW Neg 12 2.9/-
BW Paper 9-10
2.0 PS Digital 8-11
lt2.0-3.0 DSLR Digital 11-14
3.4/- High
end InkJet Print 11-13
3.0-3.2 High end chips in Digital
Backs are better
Instructor David King

dking_at_sdccd.edu
31
Digital
Photography Glossary, Definitions, and Concepts
The Inevitable Comparisons with Film COLOR RANGE
No media can capture the total color range of the
human eye. We Seecolor visually in RGB but
also feel color psychologically. High end DSLR
is roughly equivalent to Kodaks Kodachrome
Instructor David King

dking_at_sdccd.edu
32
Digital
Photography Glossary, Definitions, and Concepts
The Inevitable Comparisons with Film DETAIL and
RESOLUTION
Film is limited by the lenses and developers. It
can theoretically capture finer detail than
virtually any lens can resolve because of its
microscopic grain. A single grain of VERY
FINE GRAINED FILM averages about 2 microns
However film clumping severely cuts back on
this theoretical potential since it takes 20-40
grains to clump to reveal increments of
tonality... High end digital cameras can also
capture more than most lenses resolve though not
as much more as films potential. A Common 6
Mp DSLRs photosites are about 6 microns. In
practice it can resolve finer detail than many
films grain clumps however because each pixel
can create any tone.
Instructor David King

dking_at_sdccd.edu
33
Digital
Photography Glossary, Definitions, and Concepts
The Inevitable Comparisons with Film DETAIL and
RESOLUTION
Of course with larger film formats the grain to
image size relationship changes but it does so
with larger format digital backs as well. So how
do formats of film compare? It is commonly felt
in the professional world that you can easily
match 35mm with a 6 Mp
DSLR 645/6x6 MF with an 8 Mp DSLR 6x7 MF
with a 16 Mp DSLR Large Format with
a 20 Mp DSLR or 4-shot digital back
Instructor David King

dking_at_sdccd.edu
34
Digital
Photography Glossary, Definitions, and Concepts
The Inevitable Comparisons with Film Tonality
Rendering (Distinguishing gray tones)
Film is binary random black silver grain clumps
and clear (film) or white (paper) blend to create
the illusion of tonal increments. Digital is
capable of a very fine increment of tones based
on the BIT DEPTH of the file. This is a
computer specific issue related to the number of
bits used to define a single tone. Here is the
breakdown Bit Depth of Luminosity
Increments of RGB Colors
8 256 16.7 million 12
4,095
68.6 trillion 16
65,536
281 trillion Since human vision
can only distinguish about 100 increments this
should be OK.
Instructor David King

dking_at_sdccd.edu
35
Digital
Photography Glossary, Definitions, and Concepts
The Inevitable Comparisons with Film Image
Durability How Long will a Print Last?
This is the archival potential of a final
printed image. Answer? Ot Depends Image Type
Potential life span
under museum conditions Type C Color Print
25-35 years BW RC Print
50-75 years (is improving with new
materials) Fuji Crystal Archive Color
85-100 years BW Archival Fiber
150-200 years Normal Inkjet Dyes
5-10 years (Typical non-photo printer) Photo
Quality Dyes 35-45
years Hybrid/Pigmented Dyes 75-100
years Pigment Color inks
150-200 years Carbon Pigment BW inks
150-200 years.
Instructor David King

dking_at_sdccd.edu
36
Digital
Photography Glossary, Definitions, and Concepts
The Inevitable Comparisons with Film Time and
Cost
After the initial investment in equipment Digital
is much faster and cheaper since there is no film
and no processing. However for the professional
the real competitive advantage is speed On the
commercial world, Digital is the primary medium
for about 95 of the work shot.
Instructor David King

dking_at_sdccd.edu
37
Digital
Photography Glossary, Definitions, and Concepts
QUESTIONS?
Instructor David King

dking_at_sdccd.edu