Could use some PS help on a couple of topics:

03/04/2004 11:03:55 PM · #1

-What do all the blending options do? How do YOU use them? Examples? Links?

-What methods do you use for making fine selections?

-When cloning an elongated object from a picture (good example is phone lines) how do you not make it look like a line of editing?

I'm sure I got more but here's a start.

AFViper

Canon EOS-30D

03/04/2004 11:12:58 PM · #2

Most of the time I use magic wand to make fine selections, remember you can change the tolerance at the top of the screen. But this doesn't always work, so I have recently tried using the magnetic lasso tool which is under the regular lasso, this works sometimes.

03/05/2004 11:15:00 AM · #3

The blending options change how one layer is applied to another layer (I'm sure you've worked that bit out already)

The ones I personally use the most are:

Normal
- do I need to explain ?

Multiply and Screen
- for a duplicated layer, multiply and screen can be used to effectively under and over expose the parts in the layer

Overlay
- I use this for dodging and burning. I put a new layer over the image, and fill it with a mid grey (R=G=B=128). In overlay blending mode this does nothing whatsoever (Wow Gordon, what a great idea I can hear you say!) From there, I paint white and/or black on to this grey layer. This has the effect of lightening or darkening areas of the image. I use appropriate brushes and opacities to build up the effect. Often when I'm done I'll run gaussian blur on the layer to soften any hard transitions in my painting. Also I quite often add some gaussian noise to the layer to remove any banding effects from the layer painting. Finally I typically work pretty heavy handed on this layer, then back off the effect with the opacity slider.

Difference
- I use this mode quite a lot if I am trying to line up two layers or parts of two images that I want to combine. Difference does just what it says, it shows the difference between the two layers - helps with registration of one layer over another.

Luminosity
- I use this one for sharpening/ USM application so that any colour shifts get removed.

03/05/2004 11:27:45 AM · #4

Selections

Note: this is for photographic images only

Tools I never use
Lasso, magnetic lasso, polygonal lasso

Tools I occasionally use
painting quick masks, pen tool, freeform pen tool

Tools I almost exclusively use
USM, gaussian blur, Curves, Levels, paint brush, Convert channel to selection, select colour range, contrast mask

It depends what I am trying to select. The key idea is that a thing you want to select in a photograph has some feature that makes it stand out. Otherwise, you wouldn't be wanting to select it. So I use that particular feature to drive the selection process. The reason I don't use lassos is that they ignore the information in the image that could help me, and make my hands do all the hard work. If I'm going to draw it I'll use something like the pen tool which can follow curves very precisely and can also be adjusted with much more control than a lasso or magnetic lasso.

Select->Colour Range besides letting you select by particular colours, also lets you select by tones (shadow, mid and highlights)

If you go into the channels menu and Ctrl+left click on a particular channel, that becomes an active selection. You can then turn that selection in to a mask, and then do further work on the selection with paintbrushes and more usefully the curves, levels, unsharp mask and gaussian blur tools. This is pretty much my default method for doing quick and accurate selections on an image.

Levels, curves lets you adjust easily how strong or feathered the selection is. Blur/ sharpen lets you move edges around. paintbrushes let you do large scale adjustments or single pixel fixes.

Work paths drawn with a pen can be turned into the edge of a selection.

Selections are just active versions of an alpha channel. Alpha channels can be converted in to masks. All of them are just greyscale images.

Once you realise that a selection is the same as an alpha mask, is the same as a channel is the same as an image, and all can be easily converted back and forth between each other and more importantly edited just like a normal image - selections become an extremely powerful and easy thing to use.

You'll never go back to lasso or magic wand tools again.
All absolute statements are made to be broken, but I hope this at least encourages some to explore these useful, efficient and exact ways to make selections.

03/05/2004 11:37:09 AM · #5

Originally posted by TooCool:

-When cloning an elongated object from a picture (good example is phone lines) how do you not make it look like a line of editing?

Healing brush or clone tool (either work well in slightly different sitations)

For a black power line on a blue sky, here's what I'd do.

Select clone tool.
Use a brush that is about 3 or 4 times larger than the width of the line. Set the hardness down to about 33% or so (the width and hardness need to be played with but that should work) Opacity for this sort of fix should be high (100% or close)

Select brush blending mode of lighten (as you want to remove a dark line from a light object)

Assuming you have a horizontal line, press alt and click about 2 brushwidths above the start of the line (this is to select what you will clone over it - a clear area of sky is a good example)

then left click once at the start of the line (this should remove a real small part of the wire) Now shift+left click at the end of the wire. Your wire should be gone.

You can obviously work differently for non-straight lines and do it in sections and you'll probably need to practice a bit to get perfect results. You can also go back and do some additional touch up if that isn't perfect.

TooCool

Canon EOS-300D Rebel

03/05/2004 12:41:11 PM · #6

Originally posted by Gordon:

then left click once at the start of the line (this should remove a real small part of the wire) Now shift+left click at the end of the wire. Your wire should be gone.

Thank you for all the information. I'm sure it's just a start, but it's a lot to swallow all at once. The line above however made me say WOW cause I wouldn't believe it was that easy. Now I gotta find that power line shot...

sn4psh07

Canon EOS-10D

03/05/2004 12:45:39 PM · #7

He he -- I know which book you've been reading Gordon, you got the next edition to the one I got :-)

Canon EF 24-105mm f/4.0L IS

03/05/2004 01:08:11 PM · #8

Originally posted by sn4psh07:

He he -- I know which book you've been reading Gordon, you got the next edition to the one I got :-)

huh ? This is from a pretty wide variety of books I've read over about 10 years...

Which book have you got that covers all this ? I want a copy ;) Though I do find most of them just rip off ideas from each other - there are a whole lot with nothing new in them.

Message edited by author 2004-03-05 13:09:13.

Patents4u

Canon EOS-40D

03/05/2004 01:13:12 PM · #9

Gordon - thanks for posting this info. No time to read it right now, but a quick glance is all I needed to know that this will help me. I need much help on the editing side of things, and will give this a more thorough review at a later date.

For now, I'm off to your home state for some golf and R&R.

Canon EF 24-105mm f/4.0L IS

03/05/2004 01:13:55 PM · #10

Originally posted by Patents4u:

For now, I'm off to your home state for some golf and R&R.

Yup, great golf in Scotland - have fun!

Patents4u

Canon EOS-40D

03/05/2004 08:45:00 PM · #11

Scotland, eh? That's next year's journey.

Koriyama

Nikon D200

Nikon AF Micro-Nikkor 60mm f2.8D

03/06/2004 07:30:20 AM · #12

Originally posted by Patents4u:

Scotland, eh? That's next year's journey.

Scotland's on the itinery this year for me.

Here's what I've been using exclusively in the past 2 weeks to adjust tones, luminances and so on. (Since I bought a Japanese mag which showed how it worked.) This is more powerful than Gordon's method, although it shares a lot in common.

1 Make a tone curve adjustment layer
2 Change the tone curve any way you like. It doesn't matter how at this point.
3 Reverse the luminance (image-adjust-reverse (ctr+i)). You'll find that the tone curve icon in the layers palatte has turned black and that your tone curve change has been undone.
4 Select the paint brush and paint in the areas you want to change.
5 Gaussian blur the selection
6 Work on the tone curve.
7 You can save the selection and repeat the action with other adjustment layers, such a colour balance, hue and saturation and so on.
8 Repeat as necessary for each element in the image.

As each change is on its own layer, you can adjust the degree of effect by sliding the opacity. The beauty of this technique, over Gordon's, is a fuller control over tones and colours. (To be fair, Gordon's method is very powerful. This is more so.)

Nikon AF Micro-Nikkor 60mm f2.8D

03/06/2004 09:19:24 AM · #13

I find I typically use two or 3 layers for different features too.
I just tried out what you suggested, I see what you are saying now. All you are doing is using the mask that comes with all adjustment layers.

The inversion of the adjustment layer is inverting the mask, initially switching all the changes off. I use painted masks quite a bit but the selection methods I described above for contrast masks are a whole lot more useful than painting them yourself - try it a few times - it makes a huge difference, they are a lot more precise. The basic principle is the same as you describe, the only fundamental difference is making better use of the information you already have (the image) to develop the selection for you. Rather than painting things by hand to find features you need, you can use the underlying image to select the regions you want.

For some changes, that are not image driven (e.g., darkening around a portrait or putting more light in the eye region, painting by hand is real useful too).

My typical flow would be Ctrl+click on a channel to make it the active selection then add a new adjustment layer for whatever feature you want.

The subtle part about that step is that instead of getting a white/ all active mask on the adjustment layer that you have to start painting from scratch, the current selection is converted into the alpha channel for the layer, giving you the selection as a mask as a starting point. Then is the time to start editing the mask directly, but all the main features are in the mask - you don't need to paint them back in. If you then select the mask, you can paint on it, but you can also do all the normal filtering operations, invert it, stretch the tones, compress the tones, blur etc but you are driving your tonal changes on regions defined by the image, not by your skill with a brush tool. A combination of this and brushes is real powerful, like I described.

I think from your post about the brush method being more powerful than the method I described, that I didn't do a good job of explaining it - as what you described is a real small subset of doing image driven masks and selections. If you are at all interested in doing these sorts of adjustments efficiently and accurately, the book 'Photoshop Master Class' by John Paul Caponigro has about 4 great chapters just on the idea of how to create an effective mask and is well worth reading.

Edit: Just realised that you may not have been posting in response to the selections comment, but the overlay layer used for localised tonal adjustments. That's the problem with too many concepts in one thread :) If so - then I'm sorry for misunderstanding - but still suggest you look at image driven contrast masks.

Message edited by author 2004-03-06 09:43:41.

Koriyama

Nikon D200

03/07/2004 07:00:54 AM · #14

Originally posted by Gordon:

Rather than painting things by hand to find features you need, you can use the underlying image to select the regions you want.

Gordon, I can't grasp this bit. If I ctr+click a channel, unless I've already made some kind of selection, the whole channel is selected.

Originally posted by Gordon:

My typical flow would be Ctrl+click on a channel to make it the active selection then add a new adjustment layer for whatever feature you want.

Herein lies my question: how do you do this without first having made a selection with the brush, lasso, or other device? Am I missing something obvious?

TooCool

Canon EOS-300D Rebel

Tokina AF 28-70mm f/2.8 ATX Pro-SV for Canon EOS

03/07/2004 09:45:01 AM · #15

I also am confused at what Gordon is trying to point at here. I understand that the use of the image or part of the image itself in the mask can be very powerful, but I'm unsure at how or what instance to use this technique...

MWitt

Canon EOS-5D

03/07/2004 10:48:05 AM · #16

Koriyama

Nikon D200

Nikon AF Micro-Nikkor 60mm f2.8D

03/07/2004 10:53:55 AM · #17

Originally posted by Olympian:

Well said!