Photo luminous definition12/31/2023 ![]() If you alter a colour image by, say, using the dodging or burning tools, you are actually altering 3 greyscale channels at the same time and unless the relationship between those 3 channels stays exactly the same, there will be a shift of hue or saturation which is of course not the aim of the adjustment. This last point seems quite contradictory what has greyscale conversion got to do with colour adjustments? Well, quite a lot really when you remember that all RGB colour images are comprised of three different ‘channels’ of greyscale information, each of which represents the lightness values of each of the three colours and that it’s the relationship between them which give us the illusion of ‘colour’. ![]() What has not been mentioned is exactly why different greyscale conversions give different results, and more importantly, the fact that this principle can be used to make more accurate adjustments to colour images. Differences between the various methods are usually explained in terms of visual appeal or the ability to blend the various colour channels to emulate traditional B+W filters. Much has been written about converting colour to Black and White: we all know that there are a great many different ways to do this, some more effective than others. Warning – the following is quite advanced (even geeky) and I must assume the reader has a working knowledge of channels, levels, curves, blending modes, tools etc as well as how the main color models work (RGB, Lab, HSB).
0 Comments
Leave a Reply.AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |