WHAT WE “SEE”

(Technical Observations of a Legally Blind Engineer.)

The world is a color-less (and sound-less) place with bodies that emit, reflect and/or absorb electro-magnetic radiations traveling in all directions. The human “eye-brain vision system” (EBVS) senses a very small part of these radiations and it uses a large number of organs and does an extensive amount of processing to create the magnificent mosaic of patterns and colors that we call “vision”. It is fair to say that we don’t really “see” what’s out there. For sure we don’t “see” it all. Our EBVS perceives a part of the radiation, and “puts together” that wonderful creation that we call “vision”.

luminance (or luminous intensity per unit area), objective and measurable
brightness, (or the human perception of it), subjective, not measurable, estimated from opinions

Please note:

These “Low Vision” pages are not a study about the causes of Low Vision.
This website is not about medical advice or treatments..
Briter Vision^TM is about optical tools to improve vision.

An Engineering Debugging of Low Vision.

Low Vision is a condition of the Eye-Brain Vision System (EBVS) which produces images that,

when interpreted and communicated, find us in disagreement with others (i.e. misreading a chart), and/or,
when used by the brain to control body functions, lead to unwanted results (i.e. a fall while walking).

Low vision = poor images in the brain
- Poor images = poor data from the eye
  - Poor data = poor light-collection by the sensors in the retina,
  and/or
  - Poor transmission of data through a defective optic nerve.

(Note: other reasons may lead to poor vision. Here we focus on the light-data collection and transmission, where we can make improvements through optical means.)

It is important to know that the retina contains more than 100 million rods and cones (the actual sensors of light), but there are only one million connections (optic nerve) to bring light data to the brain: the image data from the eye is highly compressed.Considering that experts in this field state that the images created in the brain have a resolution equivalent to a 5 to 10 million “distinguishable picture elements” (pixels), it is obvious that the brain must un-compress (expand) the data to arrive to such a resolution.

(We are not experts in brain imaging decompression algorithms. In Digital Photography, where compression is used extensively, de-compressing from flawed data extends the area of the problem.)

Improving Vision: Magnification

Magnification is a commonly suggested method to improve vision. It helps because it projects the object of interest over a larger area of the retina, hence over a larger number of photo-sensors. Therefore the brain receives more data about the object of interest.

Improving Vision: Contrast Enhancement

Contrast is what makes vision possible. What we call an “image” it is a “montage of contrasts” in perceived luminance and/or color. If you have access to a computer and an image editing software you can experience the vision improvement effect of increasing contrast on a low contrast image.

As discussed in How MFV^TM Works, the EBVS auto-exposure function (or eye adaptation) continuously adjusts the eye’s sensitivity in order to create images of proper brightness: neither too dark nor too bright.

It is easy for us to estimate contrast in a photograph.

This photo shows a large brightness change from the dark left side (the counter) to the bright right side (the window) So it is a high-contrast photo.

But, limiting the attention to the counter, there is little contrast from one object to another.

The second photo shows only the counter, but now it is brighter and there is more contrast between the objects.

Vision acuity on this section is improved.

What caused this change one of two possible things:

Either a flash-light was pointed at the counter, or, and this is what was done, the bright side of the scene was covered and removed from the “sight of the camera”. The camera now only “sees” the counter and it takes a shot with a larger exposure and it reproduces it with the proper brightness level. The brain does, qualitatively if not quantitatively, the same. A “shot with a larger exposure” is equivalent to “a more sensitive eye”.

The bottom line rules to improve vision acuity, when looking at an “area of interest”, are:

VAI-1. limit your vision field to the area of interest as much as possible. And when this is not possible,
VAI-2. shield eyes from bright areas (as when we use our hands to block sunlight).