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High Definition Video In The Real World

High Definition Video In The Real World. by: Don Schultz Technical Principal The Boeing Company. SDTV sales have nearly disappeared LCD HDTV sales in 2010 expected to exceed 170 million (over 200 million HDTVs total?) HD programming exceeds 50% of total broadcasts in some areas

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High Definition Video In The Real World

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  1. High Definition VideoIn The Real World by: Don Schultz Technical Principal The Boeing Company

  2. SDTV sales have nearly disappeared LCD HDTV sales in 2010 expected to exceed 170 million (over 200 million HDTVs total?) HD programming exceeds 50% of total broadcasts in some areas There are HD alternatives for almost every channel Content quality not always consistent with true HD HD Technology becoming nearly ubiquitous 3D building momentum & UHD on horizon Proliferation of High Definition (HD)

  3. Had HDTV in our home for almost 5 years Were finding HDTV in more hotels, restaurants, bars, etc. every day (love it!) However, market pressure is also pushing the technology into other environments like aircraft where weight, power and space are critical factors and where HD could place a greater demands on limited resources HD’s Market Hype vs True Value

  4. 3 basic HD formats – 720p, 1080i & 1080p 480p = 480 vertical lines progressive scan Not HD – but the standard DVD format in the US. 720p = 720 vertical lines progressive scan 1080i = 1080 vertical lines interlaced 1080p = 1080 vertical lines progressive scan 720p & 1080i are the most common formats for HDTV broadcasting 1080p is currently the highest quality format used on Blu-Ray discs and some cable networks Not yet commonly used for HDTV broadcasting High Definition (HD) 101

  5. High definition video formats 720 & 1080 conform to a 16:9 aspect ratio 1280 pixels horizontal x 720 pixels vertical 1920 pixels horizontal x 1080 pixels vertical HD Aspect Ratio 16:9

  6. 1920x1080 refers to pixel dimensions – not resolution Total number of pixels per each format are fixed 480: 720 x 480 = 345,600 pixels 720: 1280 x 720 = 921,600 pixels 1080: 1920 x 1080 = 2,073,600 pixels HD Pixel Count 1920 16:9 1280 1080 720

  7. Pixel Density Determines Resolution & Is Not Fixed Varies With Display Size And Is Measured in Pixels Per Inch (PPI) PPI = # Diagonal Pixels / Diagonal of Display in Inches Dp = # of pixels Di = Distance in inches Pixel Density Note: Can use the Pythagorean Theorem to find both

  8. Sample Calculations For 720p 9 In: 1469 Pixels / 9 Inches = ~ 163 PPI 11 In: 1469 Pixels / 11 Inches = ~ 134 PPI 15 In: 1469 Pixels / 15 Inches = ~ 98 PPI 23 In: 1469 Pixels / 23 Inches = ~ 64 PPI Sample Calculations For 1080p 9 In: 2203 Pixels / 9 Inches = ~ 245 PPI 11 In: 2203 Pixels / 11 Inches = ~ 200 PPI 15 In: 2203 Pixels / 15 Inches = ~ 147 PPI 23 In: 2203 Pixels / 23 Inches = ~ 96 PPI Sample Pixel Densities (Dp/Di = PPI)

  9. In Ophthalmology, normal “20/20” visual acuity is the ability to recognize letters on the Snellen chart when they subtend 5 minutes of arc. Under ideal test conditions, a person may be capable of resolving two pixels separated by as little as .5 arc-minutes (~.008 deg) of angle. The human eye does even better with lines. Human Vision

  10. Resolving Video Images The human eye’s ability to resolve detail in an image (visual acuity) is directly proportional to the size of the elements of the image and inversely proportional to distance from those elements. The objective is to find the optimum viewing distance for maximum image resolution without revealing pixel detail Human Vision (cont.)

  11. Viewing Distance Screen Width (SW) Viewing Distance (VD) = SW x 2 Viewing Angle Rule of thumb for distance is twice the width of display

  12. Example viewing numbers using a 23 inch display: Screen width (sw) = ~19.5 inches Viewing distance (vd) = ~39 inches Viewing angle = ~28 degrees Compare Viewing Distance With Graphic Display Tool – Next Slide Determining Viewing Angle

  13. Equivalent View – Display Size vs Distance

  14. Real world image quality is highly subjective and depends upon many factors including: Pixel Count or Dimensions (HD or SD) Pixel Density Dot Pitch of Display Gate to gate display response time Quality of Processing & Filters (codecs, deblocking, deinterlace, etc) Displays Spatial & Spectral Resolution Contrast (fragile) Color calibration Brightness (Luminance) Visual Acuity of Viewer Ambient Light Viewing distance Resolution & Quality of Original Video Video Quality in the Real World

  15. This is a key question with no easy answer Evaluating the quality of HD video on smaller displays is difficult, subjective and leads to more questions for some… In what HD format is the visible quality lost on smaller displays? Is most of the HD quality lost on highly compressed, low bit rate video? Is the trade-off between the quantity of SD titles on the server and a marginal improvement in quality from HD content worthwhile? If there is no perceived visual benefit, is the marketing value of HD enough? HD on Smaller Displays?

  16. Objective: compare HD formats and bit rates side by side Videos encoded with SMPTE VC-1 Encoded in 420p, 720p and 1080p formats at 24fps Continuous Bit Rate – 2 Pass - Main Profile Available in bit rates from 500kbps to 6mbps 3 Display Sizes – 11 inch, 15 inch and 23 inch 11 inch – 1280x768 LCD (industrial display) 15 inch – 1920x1200 LCD (Dell laptop) 23 inch – 1920x1200 LCD (Sony SDM-P234) Note: Video quality is EXTREMELY subjective and affected by many factors including viewing conditions. Bottom Line…You’re The Judge! HD Video Demonstration & Q&A

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