I feel like we are argueing in a loop here.Does this mean that your eyes return discrete values for r,g and b? Seems to me that two posts ago you suggested a method that was not based on using your eyes at all:Using practical, hands-on subjective impressions is all fine and good. After all, that is what guide me and you through 99% of the choices that we face in our everyday life. I am sceptical about coining the term "micro contrast" based only on subjective impressions because you and Michael may not agree what it is, and a 3rd person might have another feeling about what it is. Using the word "contrast" seems to suggest that it has a physical meaning - bound to cause confusion.
I think Graeme expressed it very well a few posts ago, as follows:
What I'm keen for photographers to understand is what measurable aspects of photography correlate with what they see visually. I think that's useful and powerful for them to know so that they can understand why they like what they like and how they can use that to their visual advantage.
Now we both know that our eyes alone cannot determine precise values of RGB in a shade without the aid of another tool such as Photoshop.
What's important visually is the detection of differences
between shades, and that also applies to many other technical parameters of image characteristics, such as the MTF response of a lens.
If the difference is not great enough for it to be visually significant, then perhaps it doesn't matter from the perspective of the person producing an image.
For example, I might decide to buy a particular lens because it is claimed to have a higher MTF response than another lens at a particular fequency. It is the degree of difference, visually apparent in an image, resulting from the differences in MTF response of different models of lenses, also influenced by other considerations such as price, that helps me make a decision. If the degree of difference is so small visually, whether in absolute terms or because such differences are obscured by other factors, then I hope I would have the sense not to be influenced by such a difference.
If you really only care about subjective impressions, then technical and quasi-technical stuff should be irrelevant to you. So why care about micro-contrast or MTF50 at all? If you, like me, think that great art can be the result of subjective _and_ objective components, then we are back to the original discussion?
I've never written that I only
care about subjective impressions. I don't know how you could have drawn that conclusion. I like the term mocrocontrast
because it is so apt, so intuitive to understand and so fundamental to the modern digital process of image making. The word contrast
is fundamental to all image making, whether photography or painting. No contrast, no picture
. A contrastless picture cannot exist. It's an oxymoron, unless you consider a totally uniform area of plain shade, devoid of any detail, a modern work of art perhaps.
When addressing matters of contrast in digital images at the pixel level, or at the level of small groups of pixels, the term micro seems very appropriate to me, and meaningful. The term microcontrast is as precise as it needs to be in communicating a visual effect.
However, we should also be aware that there are certain more global visual phenomena that seem to defy the technical descriptions at the micro level.
I'm no expert in this field, but the following image illustrates very well how the context surrounding an area with a specific and precisely defined RGB value, can create the impression, visually, that the RGB value of another area in a different context has a different RGB value, when in fact it is the same.
It's clear to me that one of those orange circles is a different shade to the other. It's more brown than orange. Not only that; the grey square that contains the brown circle is very noticeably darker than the grey square that contains the paler orange circle.
Now I can't help wondering if there are any viewers who see both orange circles as being the same shade, and see the grey squares that contain each of them as being the same shade, because they actually are
the same shade technically.
Both orange circles have the same RGB value, and both squares also have the same RGB values. But please, no need to rush off to see a psychiatrist.