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Facts about Resolution
Let us first tackle HD (hi-definition) 1080....
It looks "awesome" when compared to DVD (which looks awesome when compared to VHS tape) it is, in reality, only 2 Megapixels of resolution..... compared to 10 Megapixels of resolution available from today's range of inexpensive still-photo digital cameras.
The word "hi-definition" (like hi-fidelity) is subjective and entirely relative to what you are comparing it against....
Why not 8 or 10 Megapixels of video resolution ?.... like all the still-photo cameras ?
The problem is speed.... video is a sequence of still-photos and the current standard is 30 photos (called frames) per second.... a 10 Megapixel image is greater than 4 Megabytes of information.... and multiply that by 30 and we get in excess of 120 Megabytes of data PER SECOND.... and there is currently no known way to process and store so much data that FAST.
But is it really necessary ?
With a still-photo..... we can enlarge it and study it and notice (and appreciate) all the intricate details.... but with video, constantly changing scenes prevents us from seeing such detail.... it flashes by on our screens for only a fraction of a second...we simply cannot comprehend it... ... we are not fast enough to even see it..... so we just get "an overall impression" unless we press "pause" and study it..... and 2 Megapixel video looks "incredibly good" compared to 0.3 Megapixels (standard DVD)... but going to 8 Megapixels (even if it were possible) would not appear as such a "tremendous improvement".... as I said earlier it is all "relative".
Photos on the Barbados Photo Gallery are resized.... and this is done not only to discourage theft but also because the resolution of most computer displays is less than 1 Megapixel and if I did not resize them (the whole picture would not fit on your screen) your display software would resize it anyway, automatically in most cases, so that the entire photo can be seen without the need for scrolling..... higher resolution also requires larger file size and takes longer to download and when I first started the Barbados Photo Gallery in 1996, most people where still using dial-up modems and 640 x 480 computer displays and therefore my photos back then were small by today's standards ( they look small on today's laptops and monitors)..... over time, hi-speed internet became normal and most people had 800 x 600 and then 1024 x 768 displays..... my photos simply got "bigger" as the technology advanced.
Below Standard DVD 720 x 480 frame....... Full HD 1920 x 1080 frame:
Regardless of your display (TV) size.... you are getting 0.3 Megapixels (Standard DVD) or 2 Megapixels (HD 1080) of resolution (and only IF your display actually has enough pixels (dots) on the screen).... larger screens simply have larger pixels (dots) spread out over a larger area.
Below are photo sizes from my 6, 8 and 10 Megapixel cameras:
Nikon D100 (6.1 Megapixel, 3008 x 2000 pixels, 2.7 Megabytes), Canon EOS30D (8.2 Megapixels, 3504 x 2336 pixels, 4.3 Megabytes), Nikon D200 (10.2 Megapixels, 3872 x 2592 pixels, 6.4 Megabytes)
The above comparative test photos have all been taken with the following settings: ISO 200, Shutter 1/100, Aperture F11, Lens 18mm, White Balance 6,000 Kelvin (cloudy)
Cameras should only be compared using the same Sensitivity, Exposure Value and White Balance and when set to "auto" each camera will select different values for these settings according to programming
It is quite possible to store a 10 Megapixel image in less than 4 Megabytes using compression...... if you ever wondered why the photo from a cheap 10 Megapixel camera does not look as good as one from a 10 Megapixel professional camera, compression is probably one reason...... inexpensive cameras use slower processors and slower memory, and the 10 Megapixel data stream must be reduced before processing or storage and compression is a way to achieve this... unfortunately, although the individual pixels are still there after compression, the detail information contained in them has been lost..... therefore cheap 10 Megapixel cameras take "large" photos but have poor image quality.
Below examples show the effects of JPEG compression...
Slightly compressed...... more compression...... maximum compression:
Comparing the photos:
1. On the lower left corner, see how the mesh of the gate completely disappears in certain places (at maximum compression) (the same thing happens to the wire mesh of the parrot's cage near the chair and football)
2. On the upper left corner, see the artifacts appear on either side of the electric cable in the sky area.
3. Observe the children's slide just beyond the tree..... see how it moves from "sharp" to "grainy" or "fuzzy" as the compression increases (the same thing happens to the portable basket ball hoop at the end of the garden)
4. Finally observe the pink, yellow and orange flowers on the wall of the house behind the children's swing..... and the red, orange leaves of the Crotons behind the portable basket ball hoop..... and you can see the increasing blur and lack of details of individual leaves.
On the First Field Trip of our photo course.... we explore the camera settings that control exposure..... and we practice the effect of shutter speed on flowing water....
Below photos also shows the effect of photo noise..... ISO 200...... ISO 640:
Until next time keep taking photos AND keep visiting the Barbados Photo Gallery for ideas and information
© copyright 2010 Stephen E. Mendes, Barbados.