Color Blind Photographer

[daveb2]

I am color blind, green blindness. Therefore, it is sometimes a guess if the color in a photo is accurate. 

Does anyone know if Affinity photo has a method of checking color? If a leaf is green I would like ensure the photo shows a green leaf. 

I hope you understand what I am asking.

Thanks,

[Knowbody]

What kind of color blindness do you have? red/green?

Have you seen the EnChroma glasses?

Edited December 4, 2020 by Knowbody

[telemax]

In the Adjustments panel, LUT has presets for color blindness types.

 

[daveb2]

I am red/green color blind. 

What I have read about all color blind glasses is it is questionable if they work. But I have thought of trying a pair.

[daveb2]

telemax, I see what you are pointing out. But I am not sure what that adjustment is meant to do. Does make colors appear as a color blind person would see color. Or is it a correction adjustment to the colors.

Thanks for pointing that out. I will research the adjustment further.

 

[myclay]

14 hours ago, daveb2 said:

telemax, I am not sure what that adjustment is meant to do. Does make colors appear as a color blind person would see color. Or is it a correction adjustment to the colors.

Thanks for pointing that out. I will research the adjustment further.

 

There are for each of those weaknesses* two presets available.
Simulate ; how it looks like for those which have those colour seeing weaknesses.
Daltonize ; adjusting the image so the colours can be perceived as "normal" by those which need it overblown to overcome their colour seeing deficiency.

*
Deuteranopia: green weakness
Protanopia: red weakness
Tritanopia: blue weakness

[walt.farrell]

20 hours ago, daveb2 said:

Does anyone know if Affinity photo has a method of checking color? If a leaf is green I would like ensure the photo shows a green leaf. 

That's an interesting question, but for a reason I'm not sure you've considered: there are many different colors of "green" leaves. Often all of the leaves on one tree will be roughly the same shade of green, but the next tree over may be an entirely different green than the first one. And the next one may also be different.

I'm not sure how anything that's been mentioned so far will be able to account for that, if it is significant to you in your photographic work.

[kirkt]

One thing to consider is learning how to interpret color "by the numbers" in the L*a*b* color model (also called "Lab").  There are several advantages to using Lab to assess and talk about color, even if you ultimately work in an RGB color space.  You can set up the Info panel in AP to read Lab color values and use those values to get an idea of color throughout your image - the great thing about Lab is that it inherently separates lightness in the image from color.  Color is modeled on two axes ("a" and "b") such that the "a" axis represents green-magenta and the "b" axis represents blue-yellow - this is very similar in some respects to how white balance adjustment tools characterize color temperature and tint.  Each axis is centered around 0 - that is, if a or b has a value of zero, then than represents no color, or gray, in that channel.  For the a channel, -a means more green and +a means more red.  The further from 0, the more color.  Similarly for the b channel, -b means more blue, +b means more yellow.  For clarity, negative values in Lab are often noted in parentheses - for example, a-10 would read "a(10)" using this convention.

Reading color in Lab is as simple as reading the a and b numbers and understanding what specific color that combination of numbers represents.  For example, vegetation is usually "green" but that green typically contains a lot of yellow - a typical value of green leaves might be a(10) b40, where a(10) means greenish, or negative a, and b40 means yellowish, or positive b, with more yellow than green.  If you sample an area that you know should be green and the a and b values do not make sense, it may require further investigation and adjustment.

Green in vegetation is also characterized as a "memory" color and can be affected by various cultural and individual preferences of the person seeing green; however, you can probably find a bunch of reference images with various kinds of vegetation in them and sample the various greens with an Lab color sampler tool and make note of the relationship between a and b (usually negative a and positive b) and the absolute amount and  ratio between a and b.  The de facto reference for understanding Lab color is the written work of Dan Margulis.  I know that some of his books contain specific discussions about color blindness in the context of evaluating color - for example: https://www.peachpit.com/articles/article.aspx?p=608635&seqNum=6

Instead of seeking a special tool, you can use standard tools included in all image processing applications if you familiarize yourself with "by the numbers" assessment of color, and specifically in Lab.  You will find that when you examine an image and find that several different areas of the image appear to be off, and off by the same kind of error, there is a color cast that you can isolate and correct.  Once this cast is removed, you can examine color in the vegetation, for example, and see if it falls within your range of values for a and b.

Good luck!  

 

kirk

 

[daveb2]

2 hours ago, walt.farrell said:

That's an interesting question, but for a reason I'm not sure you've considered: there are many different colors of "green" leaves. Often all of the leaves on one tree will be roughly the same shade of green, but the next tree over may be an entirely different green than the first one. And the next one may also be different.

I'm not sure how anything that's been mentioned so far will be able to account for that, if it is significant to you in your photographic work.

Walt, at least a green, (or shade of green) leaf will not look brown. But, you point to a problem I face and I assume others face, is shades of colors. In addition texture and light, strength, brightness and angle, affect the color seen. LOL

[daveb2]

Kurt:

I read your post. I have a hard time understanding or following what you are trying to say.

I am reading again and looking at other info about the LAB method.

If you could tell me again in a simplified version it would be appreciated.

 

 

[kirkt]

@daveb2 - Here is an example, with a diagram to help you get the gist.  In this image, there are four color samplers, placed on various parts of the image and set to read Lab color in the Info panel in AP.  The location of each sampler is represented by the red target (circle with a crosshair).  I placed a screenshot if the sampler reading in the info panel next to each sampler so you can see what the AP info panel readout looks like for each sampler.

 

The four samplers are:

1) the sky, reading L59 a(3) b(35)

2) a leaf on the green bush to the left of the van, reading L69 a(9) b18

3) a very red flower at the top of the bush, reading L56 a60 b37

4) the white siding on the house, in open shade, reading L48 a0 b(15).

Recall here, that for negative values of a and b I use (parentheses) around the number instead of a "-" sign.

 

Inset in the attached image is a schematic diagram of the a and b axes in the Lab color model, with a and b ranging from -128 to +127 (the 8bit representation of 256 total values).  By the way, "L" (the lightness value) ranges from 0 to 100, with 0 equal to pure black and 100 equal to pure white).

So, let's think about what these Lab values mean:

1) L59 a(3) b(35) - a little bit lighter than 50 percent lightness, slightly green (a(3)) and very blue (b35).  This is a very slightly cyan-ish blue, which is pretty much a sky color.

2) L69 a(9) b18 - brighter than 50 lightness, greenish (a(9)) and yellowish (b18).  This is a not very saturated (not very far from 0 in the a and b) yellowish green.  This is a brightly lit leaf, and that makes sense.

3)  L56 a60 b37 - just lighter than 50 lightness, VERY magenta and pretty decently yellow.  This is an intense red, and makes sense for a saturated red flower.

4) L48 a0 b(15) - middle lightness, neutral in red-green, and sort of blu-ish.  This is a neutral surface (white) that is in shade and being lit by open skylight (blue light), making the white surface appear blu-ish.  This makes sense for a neutral surface in the shade in an image that is white balanced for sunshine lighting.

 

So - does this make sense to you?  It takes practice to get the hang of thinking in a and b - but, once you start to think about color this way, it becomes very intuitive.  So, consider examining a bunch of images in AP, and pick a spot or an object in the image and try to guess what the a and b values will be (you can also try to guess the L value).  Then use the Info panel to read the actual Lab values and see how good your guess was.  This is fun and gets you into the swing of intuiting Lab color.

Once you have a handle on how Lab works, then you can study how your perception of green can be augmented with reading and editing color "by the numbers" in Lab.  You can read the Lab values for areas of an image that you think should be green and see if the numbers read as green, or the appropriate variation of green for the surface or object you are sampling.

I hope this makes sense, this is a dense topic and I encourage you to read the work of Dan Margulis if you want to delve deeper into it.

 

Kirk

 

[telemax]

This is the color wheel from AP, and a small primitive hint.
(but this is how I see it 😁)

[daveb2]

To follow up, I found a web site which, when the RGB numbers are entered, the name of the color and hue  are given. See attached photo.