Is This Doing What I Think It's Doing?

[fat0n3s]

Hi everyone.

The other day, I was trying to increase the exposure of a picture that had little to no info in the mid tones.

Thinking of a way to just select the mids, I came up with a solution that I am unsure of.

I am unsure if this meathod that I am about to explain, is really selecting just the mid tones or not.

Steps I took:

1. Ctrl - Alt ~ to select luminosity. Saved it as alpha channel named Lum.

2. While still in the selection, Ctrl - Shift - I to select the shadows. I then saved this as an alpha channel named Shadows. Then Deselect.

3. In the channels tab, I selected the RGB channel, then Ctrl clicked on the Lum channel. With the Lum channel selected, I then Ctrl - Alt - Shift clicked on the Shadows channel. I then saved this selection as a alpha channel named Mids. Then deselect.

4. I then made an adjusment layer, set to screen mode, and used the mids alpha channel as a mask.

The picture looked great, and it gave me what I wanted.

I know when you Ctrl - Alt - Shift click on a channel, WHILE a selection is already made, it only selects where the two selections come together.

In my mind, where luminosity, and shadows come together, is in the midtones.

My question is, "Is this really selecting just the mids?"

My next question is, "What other ways are there to select just the midtones?"

[Flora]

Hi fat0n3s,

I didn't try your method yet ... but will do it and let you know ....

In the mean time, to answer your question ...

My next question is, "What other ways are there to select just the midtones?"

... the simplest way I know of is Select>Color Range>Midtones...

[Panpan]

My question is, "Is this really selecting just the mids?"

There's not a lot of "mid" with this procedure. Anyway, don't you see what you select?

My next question is, "What other ways are there to select just the midtones?"

When a lasso is not good enough, you could try this:

• create a merged layer of your visibles;
• desaturate it;
• posterize (choose the appropriate number of steps; 11 if you're Ansel Adams, but let's say 3 here);
• click in the greys with the magic wand (tolerance: 0, contiguous: off);
• switch back to your working layer.

Voila! Your middle greys are selected.

[Cameraken]

Hi fat0n3s,

Flora has just given you the easiest way to SELECT the mid tones. However if you just want to alter the brightness of the mid tones then you can do this with Levels.
Just move the middle slider to lighten or darken the mid tones.
You can do the same thing with curves.

If you really want to make a mask then use Select>Color Range>Midtones

If you are interested in what this is doing then these are the steps that will give you the same result

Duplicate the layer (call it Luminosity)
Change the Blending Mode to Luminosity
Create a new layer beneath the Luminosity layer and fill with 50% gray
Merge the Luminosity layer with the 50% gray layer
The result is the grayscale representation of the image luminosity
Use a Curves Adjustment Layer to isolate the midtones by setting midtones (33% - 66%) to 100% and the rest to 0%
Merge the Curves Adjustment Layer and the grayscale layer
Load the merged layer's RGB channel as selection and invert

The resultant selected pixels are the same as those selected by Color Range Midtones.



Ken

[fat0n3s]

Thanks for the replies.

Panpan,

I haven't tried your meathod yet, but I am going to give it a shot.


Flora,

When I go into select color range, I noticed when I select the highlight, or shadow range, and save it as an alpha channel, the channel mask it gives me, looks much different than selecting Ctrl - Alt - ~.

Is this because Crtl - Alt - ~ is just selecting Luminosity, and not RGB?

Maybe the meathod I posted above is just selecting the mid tone luminosity values?

[fat0n3s]

Ken,

Thanks for the meathod. I will give it a shot to help me better understand this.