1. Digital Image Formation
File Formats Conversion & Compression

2. Digital Image Formation File Formats, Conversion & Compression
RAW: Uncompressed, undeveloped image.
Camera companies have proprietary “raw” file formats, example (Nikon – NEF) (Canon – CR2) The universal “raw” image format is “DNG” which some camera companies use.

3. Digital Image Formation File Formats, Conversion & Compression
TIFF: Tagged Image File Information
Is a “Lossless Conversion” with no information lost during the conversion process unless JPEG compression is added during the conversion.
Separates the image information into categories and assigns “tags” for each category.
Used mostly in the printing industry so different software programs can use the file.

4. Digital Image Formation File Formats, Conversion & Compression
JPEG: Joint Photographic Experts Group
Is a “Lossy Compression” which reduces the image file size by discarding information.
Separates the image into color and detail information.
Compresses color information more than detail information.
Sorts the detail information into “fine” and “course” detail and discards the fine detail first because our eyes are more sensitive to course detail

5. Digital Image Formation File Formats, Conversion & Compression
“JPEG Examples”
File Size + Compression Combinations
Large + Fine
Medium + Fine
Small+ Fine
Large + Normal
Medium1+ Normal
Small+ Normal

6. Digital Image Formation File Formats, Conversion & Compression
NUMERICAL EXAMPLES OF FILE SIZES
Uncompressed TIFF file = 14.1 MB
Uncompressed RAW file = 7.7 MB
100% Quality JPEG file = 2.3 MB
80% Quality JPEG file = 1.3 MB
60% Quality JPEG file = 0.7 MB
20% Quality JPEG file = 0.2 MB

7. Digital Image Formation File Formats, Conversion & Compression
Examples
Uncompressed “RAW” Image File
On Monday the weather was sunny
On Tuesday the weather was sunny
On Wednesday the weather was sunny
On Thursday the weather was sunny
On Friday the weather was sunny
On Saturday the weather was sunny
On Sunday the weather was sunny

8. Digital Image Formation File Formats, Conversion & Compression
Examples
Lossless “TIFF” Image File
1 Mon Lookup Table
1 Tues = On
1 Wednes whereby 2 = day
1 Thurs = the weather was
1 Fri = sunny
1 Satur = rainy
1 Sun 2 3 4

9. Digital Image Formation File Formats, Conversion & Compression
Examples
Lossy “JPEG” Image File
Last week the weather was mostly sunny

10. Review Uncompressed “RAW” Image File Lossless “TIFF” Image File
On Monday the weather was sunny
On Tuesday the weather was sunny
On Wednesday the weather was sunny
On Thursday the weather was sunny
On Friday the weather was sunny
On Saturday the weather was sunny
On Sunday the weather was sunny
Lossless “TIFF” Image File
1 Mon Lookup Table
1 Tues = On
1 Wednes whereby 2 = day
1 Thurs = the weather was
1 Fri = sunny
1 Satur = rainy
1 Sun 2 3 4
Lossy “JPEG” Image File
Last week the weather was mostly sunny

11. Digital Image Formation
File Size and Resolution

12. Digital Image Formation File Size and Resolution
STORAGE SPACE
RESOLUTION
MEGAPIXELS
RESAMPLING
FILE SIZE
LPI
DPI
PIXEL DIMENSION
COMPRESSION
GIGABYTE
PPI
BIT
MEGABYTE

13. Digital Image Formation File Size and Resolution

14. Digital Image Formation File Size and Resolution
MEGAPIXELS
1 Megapixel sensor would = 1 million pixels
12 Megapixel sensor would = 12 millions pixels
Pixels are “housed” on a sensor that may differ in size. Therefore the size of the actual pixel may be larger or smaller depending on the size of the sensor.

15. Digital Image Formation File Size and Resolution
Sensor Size
Compact
4/3 SLR
1/1.8 DX/APS SLR
A digital compact sensor
covers only 5% of the
effective image area
of a 35mm negative.
Full frame SLR
24mm (X) 36mm

16. Digital Image Formation File Size and Resolution
Pixel Dimension is the number of
pixels contained on a sensor and not the
physical size of the sensor itself
Width = 4000
Height = 3000
Width = 4256
Height = 2832
4000 (X) 3000
=12,000,000
4256 (X) 2832
=12,052,992
Nikon D MP
Canon G9 12 MP

17. Digital Image Formation File Size and Resolution
Pixel Dimension Refers to the Height & Width of an Image
Width = 3600 pixels
Height = 2400 pixels
2400 x 3600 = 8,640,000 pixels / 8.6 Megapixel Sensor

18. Digital Image Formation File Size and Resolution
Bit = The smallest unit of digital information
Byte = 8 bits
Kilobyte = 1000 bytes
Megabyte = 1,000,000 bytes OR Kilobytes
Gigabyte = 1,000,000,000 bytes OR Megabytes
The numbers are rounded off. A binary kilobyte = 1,024 bytes

19. A one bit image would classify the pixel values as either black (0)
Image Tonality
Bit Depth
A one bit image would classify the pixel values as either black (0)
or white (1).

20. Image Tonality Bit Depth
A two bit image would categorize the pixels values into four
groups: black (00), white (11), and two gray levels in between
(01 and 10).

21. Image Tonality Bit Depth
A four bit image would categorize the pixels values into 16 tonal values: black (0000), white (1111), and 14 gray levels in between (0001 and 0111).

22. Image Tonality Bit Depth
A eight bit image would categorize the pixels values into 256 tonal values per channel.

23. Image Tonality
Bit Depth

24. Digital Image Formation
Color Bit Depth
256 possible levels of Red
256 possible levels of Green
256 possible levels of Blue
256 R (X) 256 G = 65,536 colors
256 R (X) 256 G (X) 256 B =
16,777,216 color values
RGB value (200, 150,50) = ( , , ) digital