find the colour name from a hexadecimal colour code


find the colour name from a hexadecimal colour code



i want to find the name of a colour from the hexadecimal colour code. When i get a hex colour code i want to find the most matching colour name. for example for the code #c06040 , how to find out if it is a shade of brown, blue or yellow ?. so that i can find the colour of an object in the image without human intervention.

Is there any relation between the hexadecimal code of the shades of a colour? please give some sample code if there is any.




Will Python 3 ever catch on?

1:



Issue reading packets from a pcap file. dpkt module. What gives?
There is a program distributed with the Python source called pynche which can do this.
How could I check if a number is a perfect square?
The functionality you need is in the method ColorDB.nearest() in ColorDB.py.
importing same module more than once
From Python/Tools/README.
Using QTDesigner with PyQT and Python 2.6
Introduction      Pynche is a color editor based largely on a similar program that I     originally wrote back in 1987 for the Sunview window system. 


Function parameter types in Python
That editor was called ICE, the Interactive Color Editor.


Best/Fastest Way to Test Python CGI locally?
I'd always wanted to port this program to X but didn't feel like hacking X and C code to do it.


Simple way to encode a string according to a password?
Fast forward many years, to where Python + Tkinter provides such a nice programming environment, with enough power, that I finally buckled down and re-implemented it.

I changed the name because these days, too many other systems have the acronym `ICE'.

Pynche should work with any variant of Python after 1.5.2 (e.g.

2.0.1 and 2.1.1), using Tk 8.0.x.

It's been tested on Solaris 2.6, Windows NT 4, and various Linux distros.

You'll want to be sure to have at least Tk 8.0.3 for Windows.

Also, Pynche is very colormap intensive, so it doesn't work very well on 8-bit graphics cards; 24bit+ graphics cards are so cheap these days, I'll probably never "fix" that.

Pynche must find a text database of colors names in order to provide `nearest' color matching.

Pynche is distributed with an rgb.txt file from the X11R6.4 distribution for this reason, along with other "Web related" database (see below).

You can use a different file with the -d option.

The file xlicense.txt contains the license only for rgb.txt and both files are in the X/ subdirectory.

Pynche is pronounced: Pin'-chee Running Standalone On Unix, start it by running the `pynche' script.

On Windows, run pynche.pyw to inhibit the console window.

When run from the command line, the following options are recognized: --database file -d file Alternate location of the color database file.

Without this option, the first valid file found will be used (see below).

--initfile file -i file Alternate location of the persistent initialization file.

See the section on Persistency below.

--ignore -X Ignore the persistent initialization file when starting up.

Pynche will still write the current option settings to the persistent init file when it quits.

--help -h Print the help message.

initialcolor a Tk color name or #rrggbb color spec to be used as the initially selected color.

This overrides any color saved in the persistent init file.

Since `#' needs to be escaped in many shells, it is optional in the spec (e.g.

#45dd1f is the same as 45dd1f).

Running as a Modal Dialog Pynche can be run as a modal dialog, inside another application, say as a general color chooser.

In fact, Grail 0.6 uses Pynche and a future version of IDLE may as well.

Pynche supports the API implemented by the Tkinter standard tkColorChooser module, with a few changes as described below.

By importing pyColorChooser from the Pynche package, you can run pyColorChooser.askcolor() which will popup Pynche as a modal dialog, and return the selected color.

There are some UI differences when running as a modal vs.

standalone.

When running as a modal, there is no "Quit" menu item under the "File" menu.

Instead there are "Okay" and "Cancel" buttons.

When "Okay" is hit, askcolor() returns the tuple ((r, g, b), "name") where r, g, and b are red, green, and blue color values respectively (in the range 0 to 255).

"name" will be a color name from the color database if there is an exact match, otherwise it will be an X11 color spec of the form "#rrggbb".

Note that this is different than tkColorChooser, which doesn't know anything about color names.

askcolor() supports the following optional keyword arguments: color the color to set as the initial selected color master[*] the master window to use as the parent of the modal dialog.

Without this argument, pyColorChooser will create its own Tkinter.Tk instance as the master.

This may not be what you want.

databasefile similar to the --database option, the value must be a file name initfile[*] similar to the --initfile option, the value must be a file name ignore[*] similar to the --ignore flag, the value is a boolean wantspec When this is true, the "name" field in the return tuple will always be a color spec of the form "#rrggbb".

It will not return a color name even if there is a match; this is so pyColorChooser can exactly match the API of tkColorChooser.

[*] these arguments must be specified the first time askcolor() is used and cannot be changed on subsequent calls.

The Colorstrip Window The top part of the main Pynche window contains the "variation strips".

Each strip contains a number of "color chips".

The strips always indicate the currently selected color by a highlight rectangle around the selected color chip, with an arrow pointing to the chip.

Each arrow has an associated number giving you the color value along the variation's axis.

Each variation strip shows you the colors that are reachable from the selected color by varying just one axis of the color solid.

For example, when the selected color is (in Red/Green/Blue notation) 127/127/127, the Red Variations strip shows you every color in the range 0/127/127 to 255/127/127.

Similarly for the green and blue axes.

You can select any color by clicking on its chip.

This will update the highlight rectangle and the arrow, as well as other displays in Pynche.

Click on "Update while dragging" if you want Pynche to update the selected color while you drag along any variation strip (this will be a bit slower).

Click on "Hexadecimal" to display the arrow numbers in hex.

There are also two shortcut buttons in this window, which auto-select Black (0/0/0) and White (255/255/255).

The Proof Window In the lower left corner of the main window you see two larger color chips.

The Selected chip shows you a larger version of the color selected in the variation strips, along with its X11 color specification.

The Nearest chip shows you the closest color in the X11 database to the selected color, giving its X11 color specification, and below that, its X11 color name.

When the Selected chip color exactly matches the Nearest chip color, you will see the color name appear below the color specification for the Selected chip.

Clicking on the Nearest color chip selects that color.

Color distance is calculated in the 3D space of the RGB color solid and if more than one color name is the same distance from the selected color, the first one found will be chosen.

Note that there may be more than one X11 color name for the same RGB value.

In that case, the first one found in the text database is designated the "primary" name, and this is shown under the Nearest chip.

The other names are "aliases" and they are visible in the Color List Window (see below).

Both the color specifications and color names are selectable for copying and pasting into another window.

The Type-in Window At the lower right of the main window are three entry fields.

Here you can type numeric values for any of the three color axes.

Legal values are between 0 and 255, and these fields do not allow you to enter illegal values.

You must hit Enter or Tab to select the new color.

Click on "Update while typing" if you want Pynche to select the color on every keystroke (well, every one that produces a legal value!) Click on "Hexadecimal" to display and enter color values in hex.

Other Views There are three secondary windows which are not displayed by default.

You can bring these up via the "View" menu on the main Pynche window.

The Text Window The "Text Window" allows you to see what effects various colors have on the standard Tk text widget elements.

In the upper part of the window is a plain Tk text widget and here you can edit the text, select a region of text, etc.

Below this is a button "Track color changes".

When this is turned on, any colors selected in the other windows will change the text widget element specified in the radio buttons below.

When this is turned off, text widget elements are not affected by color selection.

You can choose which element gets changed by color selection by clicking on one of the radio buttons in the bottom part of this window.

Text foreground and background affect the text in the upper part of the window.

Selection foreground and background affect the colors of the primary selection which is what you see when you click the middle button (depending on window system) and drag it through some text.

The Insertion is the insertion cursor in the text window, where new text will be inserted as you type.

The insertion cursor only has a background.

The Color List Window The "Color List" window shows every named color in the color name database (this window may take a while to come up).

In the upper part of the window you see a scrolling list of all the color names in the database, in alphabetical order.

Click on any color to select it.

In the bottom part of the window is displayed any aliases for the selected color (those color names that have the same RGB value, but were found later in the text database).

For example, find the color "Black" and you'll see that its aliases are "gray0" and "grey0".

If the color has no aliases you'll see "<no aliases>" here.

If you just want to see if a color has an alias, and do not want to select a color when you click on it, turn off "Update on Click".

Note that the color list is always updated when a color is selected from the main window.

There's no way to turn this feature off.

If the selected color has no matching color name you'll see "<no matching color>" in the Aliases window.

The Details Window The "Details" window gives you more control over color selection than just clicking on a color chip in the main window.

The row of buttons along the top apply the specified increment and decrement amounts to the selected color.

These delta amounts are applied to the variation strips specified by the check boxes labeled "Move Sliders".

Thus if just Red and Green are selected, hitting -10 will subtract 10 from the color value along the red and green variation only.

Note the message under the checkboxes; this indicates the primary color level being changed when more than one slider is tied together.

For example, if Red and Green are selected, you will be changing the Yellow level of the selected color.

The "At Boundary" behavior determines what happens when any color variation hits either the lower or upper boundaries (0 or 255) as a result of clicking on the top row buttons: Stop When the increment or decrement would send any of the tied variations out of bounds, the entire delta is discarded.

Wrap Around When the increment or decrement would send any of the tied variations out of bounds, the out of bounds value is wrapped around to the other side.

Thus if red were at 238 and +25 were clicked, red would have the value 7.

Preserve Distance When the increment or decrement would send any of the tied variations out of bounds, all tied variations are wrapped as one, so as to preserve the distance between them.

Thus if green and blue were tied, and green was at 238 while blue was at 223, and +25 were clicked, green would be at 15 and blue would be at 0.

Squash When the increment or decrement would send any of the tied variations out of bounds, the out of bounds variation is set to the ceiling of 255 or floor of 0, as appropriate.

In this way, all tied variations are squashed to one edge or the other.

The top row buttons have the following keyboard accelerators: -25 == Shift Left Arrow -10 == Control Left Arrow -1 == Left Arrow +1 == Right Arrow +10 == Control Right Arrow +25 == Shift Right Arrow Keyboard Accelerators Alt-w in any secondary window dismisses the window.

In the main window it exits Pynche (except when running as a modal).

Alt-q in any window exits Pynche (except when running as a modal).

Persistency Pynche remembers various settings of options and colors between invocations, storing these values in a `persistent initialization file'.

The actual location of this file is specified by the --initfile option (see above), and defaults to ~/.pynche.

When Pynche exits, it saves these values in the init file, and re-reads them when it starts up.

There is no locking on this file, so if you run multiple instances of Pynche at a time, you may clobber the init file.

The actual options stored include - the currently selected color - all settings of checkbox and radio button options in all windows - the contents of the text window, the current text selection and insertion point, and all current text widget element color settings.

- the name of the color database file (but not its contents) You can inhibit Pynche from reading the init file by supplying the --ignore option on the command line.

However, you cannot suppress the storing of the settings in the init file on Pynche exit.

If you really want to do this, use /dev/null as the init file, using --initfile.

Color Name Database Files Pynche uses a color name database file to calculate the nearest color to the selected color, and to display in the Color List view.

Several files are distributed with Pynche, described below.

By default, the X11 color name database file is selected.

Other files: html40colors.txt -- the HTML 4.0 guaranteed color names websafe.txt -- the 216 "Web-safe" colors that Netscape and MSIE guarantee will not be dithered.

These are specified in #rrggbb format for both values and names webcolors.txt -- The 140 color names that Tim Peters and his sister say NS and MSIE both understand (with some controversy over AliceBlue).

namedcolors.txt -- an alternative set of Netscape colors.

You can switch between files by choosing "Load palette..." from the "File" menu.

This brings up a standard Tk file dialog.

Choose the file you want and then click "Ok".

If Pynche understands the format in this file, it will load the database and update the appropriate windows.

If not, it will bring up an error dialog.

To Do Here's a brief list of things I want to do (some mythical day): - Better support for resizing the top level windows - More output views, e.g.

color solids - Have the notion of a `last color selected'; this may require a new output view - Support setting the font in the text view - Support distutils setup.py for installation I'm open to suggestions! Local Variables: indent-tabs-mode: nil End:


2:


Hexadecimal web colour values are just a form of RGB.

Convert your RGB values to HSL, and then partition the Hue space into the different colours.. For example, a Hue value of about 0-19 would be "red", 20-39 "orange", 40-59 "yellow", etc.

(These numbers are not exact, I just had a quick glance at the Hue chart on the Wikipedia page.). For a more complex analysis of the colour name, use the Lightness value also.

For example, "brown" is just a darker yellow..


3:


You can build dict of hex codes as keys and human readable color names as values.. Here is a heuristic/fuzzy function for guessing what a color might look like ;).
colorof = {'f0f8ff':"Alice Blue",            'faebd7':"Antique White",            '000000':"Black"}  def get_color_name(hx):     # if color is found in dict     if colorof.has_key(hx):return colorof[hx]      # else return its closest available color     m = 16777215     k = '000000'     for key in colorof.keys():         a = int(hx[:2],16)-int(key[:2],16)         b = int(hx[2:4],16)-int(key[2:4],16)         c = int(hx[4:],16)-int(key[4:],16)          v = a*a+b*b+c*c # simple measure for distance between colors          # v = (r1 - r2)^2 + (g1 - g2)^2 + (b1 - b2)^2          if v <= m:             m = v             k = key      return colorof[k]  print get_color_name('f0f8ff') # found in dict print get_color_name('faeb11') # closest to Antique white 


4:


This page on Wikipedia provides an example of lookup from name to hex codes.

It would be fairly easy to lookup in the other direction.

Whether there is a relationship between codes and names that suits you is up to you.

You'll probably find other color-name code tables too..


5:


The Wikipedia page for web colors has quite a lot of them listed, as does w3schools and the temptingly-named html-color-names.com.

:-) And this guy has a seriously thorough page about color generally, and color on computers and the web specifically.

You could visit them, search for your color code, and see if it's listed (and if not, look for close ones).. Edit I missed the Python tag.

If you want to do this from code, the above may not be 100% useful.

You could build a pretty good associative lookup based on information from sites like that, but even with color names being somewhat subjective, it seems like there's probably a good algorithmic approach out there..


6:


Here is a small example I have written, which uses the pearson coefficient to compare two colors and chooses the most similar color from a dict.

This solution is probably not the most efficient one, but the results should be quite good:.
import re re_color = re.compile('#([0-9a-f]{2})([0-9a-f]{2})([0-9a-f]{2})') from math import sqrt  def color_to_rgb(color):     return tuple(int(x, 16) / 255.0 for x in re_color.match(color).groups())  def similarity(color1, color2):     """Computes the pearson correlation coefficient for two colors. 

The result will be between 1.0 (very similar) and -1.0 (no similarity).""" c1 = color_to_rgb(color1) c2 = color_to_rgb(color2) s1 = sum(c1) s2 = sum(c2) sp1 = sum(map(lambda c: pow(c, 2), c1)) sp2 = sum(map(lambda c: pow(c, 2), c2)) sp = sum(map(lambda x: x[0] * x[1], zip(c1, c2))) return (sp - (s1 * s2 / 3.0)) / sqrt((sp1 - pow(s1, 2) / 3.0) * (sp2 - pow(s2, 2) / 3.0)) color_names = { '#ff0000': 'red', '#00ff00': 'green', '#0000ff': 'blue' # add more color definitions here } def find_name(color): sim = [(similarity(color, c), name) for c, name in color_names.items()] return max(sim, key=lambda x: x[0])[1] print find_name('#cc0000') # returns "red"



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