Pixel: What You See Is Not What You Get!

Viewing the image contained inside a JPEG file is unlikely exactly as the digitized image originally created by your camera’s lens, sensor, and processor. What you see on your LCD screen has been grossly enlarged.  And, the image recreated by the display subsystem has been manipulated during the process to adapt the original onto its screen.

That image may have looked awesome on a smart-phone’s small LCD screen, but when that same file is viewed on a PC’s display-monitor, it somehow looks less appealing. Why?

My take: The primary reason may well be that the original image was captured using a tiny photo-sensor module. And, image quality is inversely proportional to the amount of enlargement (magnification) of the original image.

Digitization of the original capture temporarily held within the photo-sensor is where picture elements (pixels*) are created from a matrix of tens of millions of individual micro photo-sensors.  Some modules contain over 20 million individual micro-sensors; arranged horizontally and vertically in various aspect ratios.

The resultant matrix of of pixels produced and recorded into the JPEG file by the camera’s processing unit replicates an amazingly physically very small, thumbnail size 2-dimenional image matching the physical size and shape of the sensor module’s array of micro-sensors.   A smart-phone’s sensor module is much smaller than a typical digital camera.  The larger sensor modules found in full-sized DSLRs produce a more meaningful sized array, but even these represent an image just 1.5” x 1” in approximate size.

The digitized file from these small sensors hence represents that matrix of pixels at its original high density-resolution, often exceeding over 20,000 pixels per inch. I know of no displayable device that can replicate and view this image without some degree of pixel manipulation. I also doubt it can be directly printed on even the best photo papers at its original size and density. And besides, even if you could display it, you would likely need a powerful magnifying glass to examine any detail of the image.  The matrix of pixels must be altered to match the display subsystem’s  own matrix and to enlarge the the captured photo.

Smart phones have small flat display screens. The newest screens can boast as high as 500 pixels per inch. Hence, photos sourced from its own tiny camera sensor almost always look best when viewed on the same smart-phone’s screen. After all, the image has been enlarged the least, sometimes only (sic) ten times or so.

For example, my Galaxy’s digitized image file is 16MP specifically arranged 5312 x 2988 via its tiny CMOS sensor, which has a photo sensor density of over 25,000 photo sensors per inch.  Its LCD 5.7″ subsystem offers a resolution exceeding 500 pixels per inch arranged 2560 x 1440, the same aspect as its sensor module.  Hence, it’s pixel manipulation process to display the digitized image is the least obtrusive of almost any other display subsystem.

To fill the screen of my 23” PC LCD wide-screen PC monitor, the JPEG image needs to be enlarged 85 times. And, somehow the original’s pixels need to be manipulated because my monitor can only display 1920 x 1080 pixels.   If I tried to display that on my 55” HDTV screen, it needs to be enlarged over 200 times.   Rare to say the least, I’m lucky with this particular smartphone because no cropping, trimming, or stretching of the image is required when using my own external display subsystems.

No fret: Despite drastic enlargements and/or post processing pixel-manipulations, the resultant presentation by almost all flat-screen display systems is more than not, still quite impressive.  But, what is produced may just lack the punch experienced when first viewed on the small screen of the originating camera.

*   Click here for definition of “pixel.”




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