So I know basically nothing about colors apart from the very basics.
I have a color I'm trying to mimic.
I copied it, stuck it in paint, and used the color feature to get the RGB HSL numbers. Great!
RGB: 0; 49; 70
HSL: 132; 240; 33
The issue: When I try to manually input them into Excel, it "autocorrects" the RGB values after I enter in the HSL, and it "autocorrects" the HSL when I re-enter the RGB.
Why is this happening? Is this just an aspect to colors I know nothing about? Some limitation on Excel?
For reference, when I put in just the RGB, I'm much closer (but not quite there) on the color I'm looking for
HSL and RGB are two ways of "translating colors" into numbers.
HSL means Hue, Saturation, Lightness.
Hue is a degree on the color wheel from 0 to 360. 0 is red, 120 is green, 240 is blue.
Saturation is a percentage value; 0% means a shade of gray and 100% is the full color.
Lightness is also a percentage; 0% is black, 100% is white.
RGB means Red, Green, Blue, each of which is given a value between 0 and 255 in Excel.
Check this tool - https://www.w3schools.com/colors/colors_hsl.asp
If you put 0, 49, 70 for HSL you would see that it gets translated to 216, 141, 141 into RGB.
Excel is following the same logic, thus once you adjust the RGB the HSL gets automatically adjusted to represent the same color.
Excel colors are confusing because they don't follow the standard
Although the first reason you may have been confused was if you didn't know that RGB and HSL are two different ways of describing colors (and that every RGB color code has an equivalent HSL color code—see examples below), a second reason many people can get confused when selecting colors in Excel particularly is:
“Frustratingly, Excel does not handle HSL in the standard way. Instead, Excel measures all the numbers where 0 is the lowest and 255 is the biggest. But, it’s a quirk we can handle.” - https://exceloffthegrid.com/convert-color-codes/
“This approach assumes that each of your HSL values can be express in the range of 0 to 255. If, however, your HSL values are either an angle (for hue) or a percentage (for saturation and luminance), then you'll need to convert them manually before entering them in step 6. You can convert an angle value by multiplying the angle by 255 and then dividing by 360. Percentages can be converted by multiplying them by 2.55.” - https://excelribbon.tips.net/T013535_Converting_HSL_to_RGB.html
“To change the lightness (adding white) or darkness (adding black), drag your selection up and down the luminance scale on the right. Notice that the Lum value increases as the color gets lighter. Full luminance is 255 (white), and setting Lum to 0 results in black regardless of the hue and saturation settings.” - https://support.microsoft.com/en-us/office/choosing-colors-in-the-colors-dialog-box-c3d59ddf-65a7-4e62-aad7-f7b8d7684a2d
Examples of converting RGB color codes to HSL
rgb(0, 49, 70) = hsl(198, 100%, 14%)
These independent sites agree with Google that that RGB code converts to that HSL code:
https://colorpicker.me/#003146
https://hslpicker.com/#003146
So if someone told you that rgb(0, 49, 70) was equivalent to hsl(132, 240, 33), they were mistaken (even when using Excel's non-standard way of calculating HSL).
Related
I'm have a color calibrated camera and projector pair. I'm trying to come up with an algorithm based on color additivity, and I'm wondering whether color additiveness holds under the RGB space. For example, will the colors in RGB with values of (30, 30, 30) and (60, 60, 60) produce colors close to (90, 90, 90). I'm observing that this isn't the case and it produces a color like (72, 72, 72). I'm wondering whether this is due to some system error, or do I have to go into a different color space like YUV or Lab? Or whether I'm misunderstanding color additiveness and the color additive property does not apply for the addition of separate color components?
EDIT: I'm talking in decimal values.
Usually RGB integer values in domain [0-255] are 8bit values with the working RGB colourspace OECF (transfer function) applied thus non linear values. If you want to perform arithmetical operations on those values you ideally need to apply the inverse OECF to the values prior the operations.
This PDF describes the sRGB colourspace OECF for example: http://www.color.org/srgb.pdf
Just a short explanation how I came to this question. I have a ruby module which is basically a hash that gives me HTML "colours", like "slateblue", and gives me back an Array that holds the R,G,B values, like [106, 90, 205] for slateblue.
I googled how to make these R,G,B values into a lighter colour (for mouse cursor on hover effect), and several people told other people when they had a similar problem to just increase the R,G,B values. My current solution, which is a hack, is to add to the R,G,B values, like +20 (capped at 255), and then convert this into a hexstring #FF0000 something.
This seems to work okish but here is the thing now - I have absolutely no understanding about why this works.
Is it so that the 0 always denotes the lowest value of R/G/B and 255 the highest? If so, why is it capped at 255 and not at, don't know, 1024 or some other arbitrary number?
Using 8-bits per color channel - one each for red, green, and blue - yields a large number of colors (2^24 or 16777216), and is sufficient to be used in most applications. Note that there are other color formats with higher precision though.
0 is used for black, while 255 (the maximum stored in 8-bits) denotes "full-on" color.
Adding a specific number to each channel moves the entire color toward (255, 255, 255), or White. If you would like to be more exact in your lightening of the color, you might try converting your RGB color to HSL, doing your addition to the light component only, then converting back to RGB.
You can start research of HSL here: http://en.wikipedia.org/wiki/HSL_and_HSV
I have two color values in HSI (Hue Saturation and Intensity) and I want a number which represents the visual difference between the two colors. Hue is a number between 0 and 360 inclusive. Saturation is 0 to 1 and Intensity is 0 to 1.
Lets consider for example Red and Blue at Saturation of 100% and Intensity of 100%.
At this website is a way to display the color by entering in the following text.
red is:
hsv 0, 100%, 100%
blue is:
hsv 240, 100%, 100%
Clearly these are two very different colors, and so a simple way I could try to calculate the difference between colors is to use the Hue component and calculate the absolute difference in hue which would be 120 (360-240) since 360 is also equal to 0 in hue.
The problem arises where the Saturation or Intensity is very dark or light, consider a very dark red and blue.
dark red is:
hsv 0, 100%, 20%
dark blue is:
hsv 240, 100% 20%
Obviously the visual difference between these two colors is less than the bright red and blue colors, as a human would state if asked to compare the differences. What I mean here is, ask a friend "Which pair of colors is most different?" they will likely say the top bright red blue.
I am trying to calculate the difference between two colors as a human would notice. If a human being looked at two colors a and b, then two colors c and d, he could notice which ones are the most different. Firstly if the colors are bright (but not too bright) then the difference is hue based. If the colors are too bright such as white or too dark such as black or too grey then the differences are smaller.
It should be possible to have a function diff where x=diff(a,b) and y=diff(c,d) yields x and y, and I can use x and y to compare the differences to find the most different color or least different color.
The WCAG2.0 and 1.0 guidelines both make reference to different equations on perception of color difference:
contrast ratio (http: //www.w3.org/TR/2008/REC-WCAG20-20081211/Overview.html#contrast-ratiodef)
brigtness difference and 3. color difference (http://www.w3.org/TR/AERT#color-contrast).
I tried the Delta-e method(http: //colormine.org/delta-e-calculator/) but it is quasimetric so the difference measurement may change depending on the order you pass the two colors. If in your example you expect diff(a,b) to always equal diff(b,a) then this is not what you want(there may be different algorithms under this name that aren't quasimetric but I haven't looked into it past that site).
I think that the color difference metric is the closest to matching my expectations of color difference measurements. For your example it will yield that diff(a,b) > diff(c,d)
You can test it out for yourself using the tool at this website: http://www.dasplankton.de/ContrastA/
The general answer seems to be what David van Driessche said, to use Delta E. I found some Java code here: https://github.com/kennyliou/GAI
This is a answer to the question, may not be the best answer.
Suppose, in your program:
color A is a color we randomly select
Knowing color A, how can I pick a color B that will be in high contrast with color A?
The problem can be further reduced to: "imagine 2 squares filled with color next to one another. It should be unambiguously clear to a human eye that colors are not the same"
Example:
Black --> White
Blue --> White
There is some information in the Web Content Accessibility Guidelines (WCAG) 2.0 (http://www.w3.org/TR/2008/REC-WCAG20-20081211)
Visual contrast: http://www.w3.org/TR/2008/REC-WCAG20-20081211/#visual-audio-contrast-contrast
Contrast ratio: http://www.w3.org/TR/2008/REC-WCAG20-20081211/#contrast-ratiodef
Relative luminance : http://www.w3.org/TR/2008/REC-WCAG20-20081211/#relativeluminancedef
There's a good example in this site but he calculate where two colors are enough, not how to get them.
To choose a color with good contrast, I'd go with complementary colors: for example, choose the random color A, transform it to a HSV space, get the complementary hue.
Complementary hue: after you transform color from RGB to HSV, complementary hue will be 180 degrees appart (or 0.5, in a 0-1 normalized hue value). This site has something about it in PHP
As I was searching for a better way to do this, i stumbled across the Adobe Illustrator guide which mentions how they create complementary colors. They say:
Complement Changes each component of a color to a new value based on the sum of the highest and lowest RGB values in the selected color. Illustrator adds the lowest and highest RGB values of the current color, and then subtracts the value of each component from that number to create new RGB values. For example, suppose you select a color with an RGB value of 102 for red, 153 for green, and 51 for blue. Illustrator adds the high (153) and low (51) values, to end up with a new value (204). Each of the RGB values in the existing color is subtracted from the new value to create new complementary RGB values: 204 – 102 (the current red value) = 102 for the new red value, 204 – 153 (the current green value) = 51 for the new green value, and 204 – 51 (the current blue value) = 153 for the new blue value.
It wouldn't be too hard to do this programmatically and think this time that it might actually work for what you are trying to do.
Good Luck!
how to get RGB values in percentage in photoshop.
and is cmyk percentage values are similar to RGB?
RGB and CMYK are different color modes.
RGB colors are screen colors. It is expressed in absolute values, usually in integer values from 0 to 255, representing the brightness on the screen. The exact range of values depends on the color depth of the image. The higher the value, the more light of that color is added, so the highest color is white.
CMYK colors are printing colors. They are used to represent the amount of ink used for a pixel. This is no absolute value, because it is merely a ratio between the color components. The higher the value, the darker it gets. 100% of each is (near) black, although real black is usually constructed by using 100% of K (key) and about 30% of each of the other components.
integer values from 0 to 255 are for 8 bit color, in the day of 16 or 32 bit color it would make sense to be able to view rgb as percentage values.
this is being added to Adobe lightroom currently does percentaes unless you're in the develop module, in soft proof mode