Relative RGB: it offers to the user to mix the three channels R, G and B, but with control for the limits.You can enter positive or negative values with a sum that is lower, equal to or higher than 100%. Absolute RGB: it offers to the user to mix the three channels R, G and B without any control for the limits.settings at user disposal based on four criteria:.predefined settings (Normal contrast, High contrast, Luminance, Portrait, Landscape, High and Low Sensitivity, Panchromatic, Hyper Panchromatic, Orthochromatic, Infrared).With these two possibilities that you have to experiment with, you can create special effects and color filters such as infrared, but also some common settings such as landscapes, portrait, contrast, etc. The same reader will look only for positive values (because they are logical) and no negative values.īut don't let this stop your creativity, open your mind to : The sensible reader with a mathematical mind will notice that the sum of the 3 channels should be 100% to avoid clipped highlights. It amounts to take a percentage of each channel (R,G,B) and put them together ! There is however a simple explanation: this method uses a channel mixer in order to carefully manage the balance between the different color components of the image, to reconcile the distribution of the lights, mid-tones and shadows. Move this control point downwards to darken (or upwards to lighten) this tone.Īt first sight this method seems to be very complex ! For example, choose with the pipette a tone area you want to darken. There is a gamut control, but it doesn't prevent you to obtain very good special effects by pushing the curve to extreme values. Unlike some other commercial software that act only on a limited number of colors with sliders, you can interact on the whole color palette with Rawtherapee.įinally, the R, G, B values are set at the same level to ensure a perfect gray tone. The algorithm uses a conversion rgb=>LCH =>rgb with gamut control. This method use a flat curve, that allows to modify the luminance based on hue. in "Lab Adjustments" it is chromacity C=sqrt(a*a+b*b) that is set to 0. In "Exposure" it is channel “S” from HSV that is set to 0. Note: the other 2 methods of desaturation in Rawtherapee (quoted above) give other results due to different algorithms. This ensures a totally neutral gray image. This method works in such a way that for each pixel (R=G=B) is given an equivalent luminance value of L=0.299*r + 0.587*g + 0.114*b. Note also the interaction with the Color Toning tool, see Color Toning section below. Nevertheless only the methods in the current tool gives you the maximum of possibilities for a black-and-white conversion.įor a perfect gray tone, except in the case of Color Toning, as "Ajustements Lab" are treated at the end of the pipeline, the values of “a” and “b” in the Lab Adjustments of the "Exposure" tab are set to zero. by enabling Film Simulation in black and white (films Ilford, Kodak, Fuji.).by setting the Chromaticity slider in the Lab Adjustments tab to -100.by setting the Saturation slider in the Exposure tool of the Exposure tab to -100.Please note that Rawtherapee can produce black-and-white images without the use of this tool: The Black-and-White tool is organized in three methods, each producing a different black and white result.
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |