Re: Common standard for defining a color?

Hi Norbert (and others)! On 3 Feb 2004 at 18:44, Norbert Mocsnik wrote: > I don't know if any standard exists on Earth regarding color > information storage in arrays.. What about mixing the two ways you > wrote about? array("rgb" => array("r" => $red, "g" => > $green, "b" => > $blue), > "a" => $alpha); > or > array("cmyk" => array("c" => $c, "m" => $m, > "y" => $y, "k" => $k)); So > it can store any combination of color information.. - it's easy to > construct this kind of arrays - it's easily readable Well, the additional "array inside an array" makes it unnecessarily complex in my eyes. You can have a function that checks if "c" and/or "m" or something is set and assume that it's cmyk - you don't need another level of complexity. So if you vote that we should move from the array with indexes 0 to 2 of of Image_Color currently to "r","g" and "b" (as Toby introducted in Image_Text) I'd prefer that solution. What about others? > In my opinion alpha range should be 0-255, and it should be > transformed to any range whenever needed. You wrote: > > imagecolorallocatealpha() defines a range of 0..127, whereas 0 > means > "completely opaque" and 127 "completely transparent". > I still think the alpha range should be 0-255. > > Afaik an alpha-value of 0 is "fully transparent" in most > > programs, right? > In Photoshop it is, and I prefer this way (0 is "fully transparent"). Agreed. That's how I would have expected it to be. And I think this way around it's the "natural way". > Image_* packages really should follow some convention, I think this > question was generally a good idea from you. Thank you! Let's hope others will join this discussion. Please comment! Regards, Stefan > Stefan Neufeind wrote: > > > Hi colleagues :-) > > > > Investing a bit further deep into the field of colors (for usage in > > new Image_Graph) I stumbled over a question that I'd like to have > > discussed on this list. How do we define a color? Let's start with > > RGB-color, since this will be the most used one: > > > > Image_Color uses an array with indizes 0,1,2: > > array($red, $green, $blue) > > > > Image_Text uses an array with indizes r,g,b to indentify the colors: > > array("r" => $red, "g" => $green, "b" => blue) > > > > I see a good point for choosing the Image_Color-way because the > > array is easier to construct. However I like the Image_Text-approach > > a bit more in reference to "easily readable code" etc. In which > > direction should we go? IMHO it would be good to decide on a > > solution that's used all across those Image_*-packages etc. because > > otherwise you would have to convert between those array-formats - > > not much usefull in my eyes. I'm thinking about a way to handle CMYK > > etc. also. So going the Image_Text-way might be preferable? Please > > comment expressing your feelings about this! > > > > > > And one more question that arises: How would I best add an alpha- > > value to those arrays? For the Image_Color-approach I would simply > > add a fourth value, for the Image_Text-way an "a" => $alpha. Right? > > > > imagecolorallocatealpha() defines a range of 0..127, whereas 0 means > > "completely opaque" and 127 "completely transparent". But since the > > colors have a range from 0 to 255 and 255 defines full intensity for > > a normal color, wouldn't it make more sense to use an alpha of 255 > > as "opaque"? Afaik an alpha-value of 0 is "fully transparent" in > > most programs, right? Pierre, could you please tell me a bit about > > this?