A new algorithm for adjusting exposure automatically

I'm working on an algorithm that aims at adjusting exposure, and histogram black and white points automatically.

Here are some examples I have obtained so far. The pics on the left are converted in DPP using the following parameters :
exposure : 0
picture style : neutral
contrast : 0
Highlight : 0
Shadow : 0
RGB Histogram black point : 0
RGB Histogram white point : 255

The pics on the right are converted with the same parameters except the exposure and the white and black points which are calculated automatically by the algorithm.

What do you think ? I have tried different kind of pics but I'd like to try the algorithm on pics that have big problems with exposure to see how the algorithm behaves on them. So if you have such pics and want me to try the algorithm on them, you can send me the RAW file (the RAW file is necessary) and I'll send you the result or post it here depending on your desire.

sorry if i sound like a noob...but is this solely for DPP?

for PS you can make a droplet that can do an auto levels which moves the white point and black points automatically for you to maximize the tonal range.

ccp900 wrote in post #11342415
sorry if i sound like a noob...but is this solely for DPP?

for PS you can make a droplet that can do an auto levels which moves the white point and black points automatically for you to maximize the tonal range.

yb98 is a POTN member who is a software developer. In recent months he put out a DPP add-on with some nice features called DPP++. You can check it out if you click the link at the bottom of his post in his sig. There are also numerous thread here where he announces an update -- search for "DPP++" and you can find good info.

Once in a while he gets into a "problem solving" mode while working on a new feature about something and some of us chip in although we don't have a clue about what we're talking about!

ccp900 wrote in post #11342415
sorry if i sound like a noob...but is this solely for DPP?

for PS you can make a droplet that can do an auto levels which moves the white point and black points automatically for you to maximize the tonal range.

Well I see 2 main reasons for doing auto-adjustement in the raw converter rather than in PS :

1. in the raw converter you have more information than in PS as information is coded in 12 or 14 bits in the raw converter while it is 8 bits in PS. You can of course work in PS on 16 bits tiff images but this will introduce another step in the workflow as you have to convert first to tiff and then convert to jpg when you finish. Furthermore even if you work on 16 bits you will not have more than 12 or 14 bits of real information anyhow.

2. People usually would prefer to do everything in their raw converter and avoid to open another software, except for working on particular images. But when you have hundred of images, you'd like to do all your work in the raw converter.

For the moment, the algorithm is under DPP, but if it works nice, I think it is possible to transpose it to other converters like Lightroom.

By curiosity, I have applied the auto-tone feature of PS and here is a comparaison between both algorithms. At the left is the auto-tone feature of PS. I see that PS modifies the colors in the last pic.

ahhhh that clears a lot of things up LOL thanks guys!!!

if you were to apply the PS toning but use the overlay ofluminosity only, it might not affect the colours so much.

One thing I've not messed with much is the handful of one-click toning adjustments that are in the RGB tab of DPP. yb98 have you checked them out for comparisons with what you are doing?

I like the results- looks good!

I have done some other tests with a pic which presents a flat and low contrast looking (it was taken through a window) and as Tony suggested I have included the DPP tone curve assist feature in the tests. I could not test the auto lighting optimizer of DPP as it was grayed. I think it is available only with some cameras.

The following six pictures represents the following conditions :

. Top-Left : the original picture converted in DPP using the same conditions as in post 1
. Top-Right : the pic adjusted with the new algorithm
. Center-Left : the pic adjusted in photoshop with the auto-tone feature
. Center-Right : the pic adjusted in photoshop with the auto-contrast feature
. Bottom-Left : the pic adjusted in DPP using the first tone curve assist button
. Bottom-Right : the pic adjusted in DPP using the second tone curve assist button

It seems that the algorithm behaves well but I still need to check it on some other kind of pics. If it still works well I think it will be the next new feature of DPP++.

Lookin' good!

I'm not talking about the Auto Lighting Optimizer -- that's only available for the newer cameras that have that feature.

In the RGB tab, if you look at the top, you'll see a little panel called Tone Curve Assist. It has three little buttons -- the first is for a "normal" adjustment, the second for an "amplified" adjustment and the third to Reset the adjustments. They are not dramatic, but I figured you could play with them for comparison. Interestingly, even though they affect the RGB histogram they don't alter the luminosity slider values at all.

Yes That's what I did. The bottom pictures are obtained in DPP by using these buttons. They modify the shape of the curve but not the values of the sliders.

The results from your stuff look pretty nice to me. Is there any chance of this stuff making it into an LR3 plug-in at any point? Or are you solely working with DPP for the time being?

For the moment it's for DPP, but why not investigate the possibility to make it an LR plugin when I'll have enough time...