[Nexus 5 Original Android Development] rajendra82:
I am now ready to unleash the profile builder spreadsheet. There are three tabs with increasing level of complexity. All tabs have two buttons. Import will read a profile and paste it into original registers column, while export will give you the ability to save the new register array. The created profiles will all have same positive and negative register array values, and when importing, the negative register array values will be ignored.

1. The first, and easiest tab to understand is the simplified editor. It attempts to provide 3 overall controls, and 3 for each color as well. You are familiar with the names, contrast, brightness, and gamma, but what they do needs a little explanation. Contrast is a multiply control. It increases the slope of the color curves. This will mainly affect the bright colors. Brightness is an additive control, this adds a constant value to the curves. This mainly affects the dark colors. Gamma bends the curve up and down compared to the ends. It affects the mid tones. The gamma is a correction multiplier, so if you start out with a gamma of 2.0 and want to get to 2.2, you need to apply a correction of 1.1. I tried to incorporate the results of latest mag01 testing into the controls, so red curve is very sensitive to changes, green a lot less so, and, blue the least sensitive. This is all theoretical, so if you apply a correction, the spreadsheet may over or under correct, and you will have to import the modified profile and fix problems. The overall controls apply to all three colors, while the individual color controls only affect the curve for that color. The dashed line on the graph shows the original curve, and the solid line shows what will happen after you apply correction. If you go too far on the controls, the curves can start to hit the ends, and this will cause clipping (near white colors will look like a solid blob, or near black colors can all turn pitch black) if you apply such a profile.

The controls also interact with each other, so changing the brightness can change overall contrast, and gamma, even though you didn't purposely apply corrections for those. It would probably be best to make changes to one thing, fix any problems this creates, then change another, and so on. You will probably end up making smaller and smaller changes for multiple rounds, until things converge on what you wanted to do.

2. The second tab is a five point correction, where you can take a profile, and move it at one of five important inflection points. The rest will be calculated by linear interpolation. The changes you make are on the intensity scale, so higher values than where you started represent boosting that part of the curves, while lower values represents suppressing it. There is a point called register 6.5, which is actually halfway between registers 6 and 7. It affects both of them. You can see the changes in curves just like on the first tab.

3. The last one is good old manual tweaking. You could easily do this in a text editor, but you already made it this far, and like the interface, so if you want to smooth out localized kinks between the inflection points and finish what you started, you can use this tabs.

This is by no means perfect, but I think it's a start. The sheets are protected, letting you only make changes to the cells you need to, but that's only from you inadvertently deleting some vital formulas. I am not hiding anything secret, and there is no password, so you can unprotect the sheets and change those other normally locked cells, if you want to. There is a couple of macros used by the buttons to save the profiles. Try as I might I could not get these to save directly to the phone. I had to save the profiles to a place on the computer, and then put them on the phone afterwards.

https://www.dropbox.com/s/wkpadoxaa3p1bsa/Nexus5_Color_Profiler.xlsm