We are delighted to publish Jerry Jobe’s latest mobile photography/art tutorial for our reading and viewing pleasure. This time Jobe takes another look at the app called MaxCurve. This is Part 3 of 3 Tutorials that we have published on this app. (If you missed Part 1, please go here and for Part 2, please go here). Read Jobe’s thoughts as he puts it through its paces (foreword by Joanne Carter). Take it away Jerry…
MaxCurve retails for $2.99/£2.29 and you can download it here.
“In the first part of my series on MaxCurve, I showed how MaxCurve implements the standard RGB curves. In part two, we saw how curves could be applied to controls like Opacity, Contrast, Hue, and Saturation that normally don’t use curves. In this final part, we will venture into more uncharted territories by discussing an entirely new colorspace – LAB.
First of all, what is a colorspace? It’s a method of mathematically describing all the colors we can see in an image. The most common colorspace is RGB, which describes each color as a combination of the three different color channels. Since RGB describes the color of light, a value of 0 in any channel means a lack of that color light. If all three channels are 0, we have no light at all – it’s pure black. If all three are 255, the maximum value, then we have all the light available – it’s pure white.
The second common colorspace is CMYK, which is used in printing. These are the colors of inks available to print on white paper – Cyan, Magenta, Yellow and blacK. The absence of ink (value of 0 in all four channels) is white, and all other colors can be described by a combination of the four ink colors. You will often have to convert RGB values to CMYK when sending work to a professional printer.
The their colorspace is LAB. L stands for Lightness or Luminosity. Looking at the L channel is exactly like looking at a grayscale version of the photo. The other two channels, the a and b channels, are not abbreviations of anything. The a channel is the green to magenta spectrum, which is often referred to as tint. The b channel is blue to yellow, referred to as temperature or warmth. Working in this colorspace can give you some wonderful results. As far as I know, working with a and b channels is only accomplished on the desktop with Photoshop, and only accomplished on mobile devices with MaxCurve.
I do want to mention that everything I say about LAB color comes from a terrific book by Dan Margulis, “Photoshop LAB Color: The Canyon Conundrum and Other Adventures in the Most Powerful Colorspace”. (Yes, an entire book on this set of curves. Believe me, it’s that deep).”