Digital Outback Photo
- Photography using Digital SLRs

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Digital Outback Fine Art Photography Handbook

© Bettina & Uwe Steinmueller

 
 
9 Digital darkroom basics
 
 

9.1 Photoshop Overview

9.2 Color Profiles for Beginners

9.3 The important image formats

9.4 Features of Photoshop used often by digital Photographer

9.5 Selected Photoshop tools

 
 

You are probably aware that the topic digital darkroom can fill many, many books. Sorry but this chapter will not replace any one of those books. For us clearly the center of the digital darkroom is Adobe Photoshop. There are many nice image editing but still Photoshop remains the standard, period. Our book recommendation are found here.

So if you want to save buying Photoshop think twice.

 
 
9.1 Photoshop Overview
 

Getting into Photoshop seems like a huge task and it is. The only way through the jungle we see is learning as you go. Try to understand what you need for your task at hand and go from there.

Fortunately as a photographer you only need most often only parts of Photoshop and we will mention some of them here.

 

Here is an initial list of things you will do in Photoshop (as far as this handbook is concerned):

  • Setting up color management
  • Open files
  • Changing contrast (Levels & Curves)
  • Correcting & Enhancing color
  • Sharpening
  • Retouching
  • Working with Actions
  • Cropping
  • Resizing
  • Using Plug-ins
  • Know the difference between 8 and 16 bit more
  • Saving in different formats
  • Printing
 
Before we will get into these topics you need to understand some basics about color management.
 
 
9.2 Color Profiles for Beginners
 

Color correction and color management is one of the most important and difficult areas in digital photography. We are not experts on this subject. We want to share what we have learned and invite all who know better to correct our faults and improve this chapter for the use of all interested in this subject.

If you have a photo on the web and different people discuss the quality of the colors of a photo they most of the time have the following problem:

  • Different monitors show the same RGB value quite differently

So besides there many opinions on color they actually see different versions of the same photo.

But the real challenge is to get the right impression on a monitor how a certain photo would print on a color printer. The new inkjet printers from Epson (HP, ..) can produce amazing results. But without color management it remains trial and error. You end up to change the color settings of the printer for every print without very much being satisfied. So what does color management mean? In our example it means that the photo you see on the monitor looks very close to the result you get from your printer. This is called "soft proofing". With very costly monitors the match can be very close.

The reason for this dilemma is that every device: monitor, printer, scanner and digital camera has very different capabilities to render colors. If there is a fixed RGB value the display of that value on that device will be different and certain values the device might might not be even capable to render. The colors a specific device can render describe a gamut of colors. Color management is based on a standardized description of that device (so called ICC profiles). You either get these profiles from the device manufacturer or measure it with special calibration hardware.

As most people like to use there monitor as there "soft" proofing device. That is why the first step towards a color management is the calibration of the monitor. Be aware that very precise calibration also is influenced by the room and even your clothes. Adobe Photoshop comes with a utility called Adobe Gamma which lets you calibrate your monitor. Although this is much better than not doing any calibration at all it is better to use some hardware calibration device. We uses different tools like Optical/X-Rite, Optical/Spyder or GretagMacbeth Eye-One. To do the calibration just follow the instructions of your tool. The monitor should be on for more than 30 minutes and don't change any monitor settings without any re-calibration, a re-calibration is anyway recommended about once a month.

Profiling LCD monitors can very tricky and the success depends on the tool and the monitor brand. We use a LCD monitor not because it is the best proofing device but we think it helps with our eyesight as we are also writing a lot using the same monitor.

How to find our which monitor profile Photoshop is using:

Select "Edit->Color Settings" and use the drop down list where you can select working spaces and scroll (mostly up) till you find the entry "Monitor RGB" (above shows Sony_LCD_std_D50). This entry shows the monitor profile which gets used. Then "cancel" the "Color Settings" dialog so that you do not change your working space!

Let's see where we are:

We have some RGB values of the image (YMCK is excluded from this discussion as we only work in RGB). These values are mapped to the monitor using some monitor profile and also mapped to the printer by using a printer profile. This would probably work for this close loop. But what if you send the image file to an other person. He would need your monitor profile and then map it to his monitor profile (which is certainly different). You might envision that this would not work in the real world. Up to this point we have only discussed about profiles for individual concrete devices. The ICC solution for this dilemma is the introduction of abstract standardized color profiles/spaces (e.g. Adobe RGB (1968), sRGB, Apple RGB, ...).

These are very well defined profiles which might not match any device in the world. The solution is now as follows (we assume the color space Adobe RGB -this is the one we use). The image internally stores all RGB value in relation to the internal (abstract) color space (here Adobe RGB). Photoshop's ICC engine now translates all these RGB values from the internal space to the concrete monitor space (using a monitor profile). The same happens when you print.

Now sending the image to an other person is no problem as the same happens there again. The information about the profile is stored by Photoshop (also other applications like Bibble, Qimage,...) within the image (TIFF, JPEG). The abstract standardized color spaces range from a narrow gamut to broader gamut. It is quit obvious that if you image is working with a narrow gamut that some colors get lost as a transformation which broadens the gamut has to "invent" missing colors and that is not possible. If the gamut is to wide you deal with colors which probably none of your target devices will ever be capable of rendering.

 
9.2.1 Some Standard Color Spaces
 

The following table discusses some of the most important abstract color spaces:

NTSC This is the space for the US television. It is even worse than the European PAL standard. It is presented here that some believe the Nikon D1 uses this space to create the non RAW/NEF files. It looks as if that is not a very good choice. As I understand this is not an issue for RAW/NEF files
sRGB This space is still pretty narrow but is supported by some printers (Epson 1270) and scanners (Nikon LS 2000). It might be a good idea to use this for photos on the WEB.
Adobe RGB (1998) This is a very popular space among Photoshop users. It covers most printable colors. This is what I use.
Pro Photo RGB Colorspace supported by Kodak (wide gamut)
Apple RGB Not as wide as AdobeRGB
Bruce RGB A space designed by Bruce Fraser which is a bit wider than the Adobe RGB space
 
9.2.2 Monitor Profiles
 
By now it should be clear that all good color management starts with a good as possible monitor profile.
 
 
9.2.3 Camera Profiles
 
Also profiles for you camera are very important. We will discuss this later in the chapter "Raw File Processing". There are two types of profiles: Camera Generic (used by most RAW conversion tools) and specific profiles for certain light conditions. This is an important distinction as for an optimal profile all the parameter have to be constant (light, RAW processing options, exposure)
 
9.2.4 Printer Profiles
 

There is actually no profile for a printer. The profile is always for one paper, the same ink, the same individual printer and the same printer driver used. Profiles for different papers can vary significantly.

We will talk about printer profiling in more detail in our chapter about "Printing".

 
9.3 The important image formats
 

 

TIFF This is the standard high quality image format without any loss. It comes in 8 and 16 bit versions
JPG Important standard compressed file format. There is a quality loss even at low compression levels. Mostly used for the web or transmission over slow connections.
JPG 2000 Newer improved version of JPG. Not widely used yet
STN Storage Format of Genuine Fractals for use in image upsizing (see later chapter)
PSD Photoshop format which allows to store some internal information (like layers) with a file. Can be useful for intermediate files.
GIF For Web usage as there are only 256 colors available
NEF Nikon RAW image format (compressed and uncompressed)
CRW Canon RAW image format
other RAW formats There are also RAW formats from Kodak and Olympus

 

 
For most of our work we use only TIFF to avoid any quality loss.
 
 
9.4 Features of Photoshop used often by digital Photographers
 

9.3.1 Setting up color management

 
Here we recommend reading this article by Bruce Fraser (a Photoshop authority) about setting up color management in Photoshop 6.0.
 
9.3.2 Open files
 
You can open with Photoshop all of the important standard files. Only the proprietary RAW formats of the digital cameras can only be used if the vendors provide camera file format plug-ins or they are supported by third party vendors (e.g .Bibble's Photoshop plug-in)
 
9.3.3 Changing brightness and contrast (Levels & Curves)
 

There are two main operation you really need to understand.

Levels:


Levels Dialog

 
The Levels dialog shows in the middle the histogram of the image. I shows here the gray values from 0 = black to 255 = white in 256 steps. (there are also histograms available for the color channels (red, green and blue)
 

Best to explain some basics is to have a short example.

 
This first histogram indicates that there is a small gap on the left and a larger on the right. This photo does not make use of the full range from black to white.
 
 
Shifting the right(white) and left(black) triangle towards the borders of the histogram we get a more contrasty yet lighter image.
 
 
By sliding the middle triangle (gray) to the right we enhance the contrast and get a slightly darker image. We hope you can see how this very simple operation improved a flat looking image significantly.
 

Curves

 
 

Curves allow you to do the same corrections as levels and more. The difference is that levels does simple linear transformations and you can do with curves much more sophisticated corrections. You probably need some good Photoshop book to better understand curves.

Here are some basic but important curves:


darken the image


brighten the image


Boost contrast (S-Curve)

 
9.3.4 Correcting & Enhancing color
 

Colors need often to be corrected (see also White Balance - WB). Some global corrections can be done also using Levels and Curves (working on selected color channels). But Photoshop also provides more selective tools to correct colors.

We try to do as little selective color corrections as possible which is possible if you use good camera profiles and tools for changing WB or removing casts. Actually the tools of choice for use are most often some specialized Photoshop plug-ins (see below)

 
9.3.5 Sharpening
 

In the next chapter about Raw File Processing we will also discuss the need for sharpening and mention some methods. Also here we often use specialized Photoshop plug-ins or Fred Miranda's sharpening actions to get better results. Sharpening is an endless field by itself and there is no perfect way. Be sure that your picture is as sharp as possible to begin with:

  • No camera shake
  • in Focus
  • Right DOF (depth of field)
  • Right panning if photographing moving objects
  • Use a rigid tripod whenever possible

TIP: Never only judge sharpness on your screen. What counts is the sharpness of the print. Especially inkjet prints can take a lot of sharpening (looks over sharpened on the screen) and deliver great prints. Nik Sharpener does sharpening based on target printers and targeted resolution.

 
9.3.6 Retouching
 

We already discussed that sometimes sensors collect dust and these spots are easily to spot in brighter parts (e.g. sky) of the image. Here you can use the Photoshop clone tool to copy over some similar other areas of the image.

With the introduction of Photoshop 7.0 there is a more sophisticated clone tool available: The "Healing Brush". The healing brush melts the source and target areas together and gets much more pleasing results. For us this tool alone was worth the whole upgrade from Photoshop 6.0 to 7.0.

 
               
 

The above images are 100% pixel crops from a real life example (original was 3000x2000 pixels). The area is shown before and after the use of the Healing Brush. These spots would also have been easily removed just using the clone tool but there many situations where the "Healing Brush" is easier to use and provides much better results.

We also (but really rarely) use the clone tool to remove unwanted parts from the photo.

 
9.3.7 Working with Actions
 

Once you have found out how to deal with certain operations in Photoshop you will do the same sequence over and over again. Here Photoshop allows to record so called actions which are exactly the sequences you want to repeat over and over again.

Recording a new action is very easy. You click on and you get this dialog:

Name the action and select one set (the actions can be organized in sets) you want this new action be part of. One you click on "record" all operations will be recorded which is indicated by the red recording sign:

After the last operation you wanted to record hit and the action is ready to be used. To replay an action select it and and hit .

It is also possible to leave out some steps by unselecting this checkbox for a certain step. This icon indicates that the action will stop at this step and display the steps dialog. This allows you to have some default settings recorded but then later to overide them at the time of playback.

Tip: Learn how to work with actions as soon as possible. It will save you time and provide a more consistent workflow.

Fred Miranda even developed a market for sophisticated ready to go actions. You can buy these actions for reasonable price at his site (e.g. noise removal, linear RAW file processing, enhancing saturation, ..). You can be sure there is a lot of work and knowledge behind each of his actions.

 
9.3.8 Cropping
 
Pretty often you might want to crop your image and Photoshop allows you to perform a rectangular selection and the crop the image to these dimensions.
 
9.3.9 Resizing
 

There 2 basic purposes for resizing:

  • Downsizing - making the image size smaller - less pixels (mainly for web usage)
  • Upsizing - making the image larger - more pixels -(mainly for printing)
 
It should be pretty clear that downsizing is easier as you lose information while upsizing has to invent information (which can be only done so that the faked information blends in well).
 

If you downsize an image by some magnitude you should sharpen it afterwards.

Upsizing will be discussed in full detail in our chapter about "Printing".

 
9.3.10 Photoshop Plug-ins
 

There is a whole universe of plug-ins which are all sort of filters and other applications which can be used inside Photoshop using the Photoshop plug-in API. Some plug-ins might even cost more than Photoshop itself.

Plug-ins allows Photoshop to grow in all dimensions and we often use more the plug-ins than Photoshop itself.

 
9.3.11 Know the difference between 8 and 16 bit data
 

Photoshop knows two data modes:

  • 8 bits/channel
  • 16 bits/channel
 

Most digital RAW formats allow to get 12 bits/channel and these then get represented as 16bits/channel in files (mostly 16bit TIFF).

Why are these 4 more bits so important? If you images came perfect out of your camera it would not make such a difference as most printers only use 8 bits anyway. But there is hardly any image which does not require at minimum minor corrections. But once you start correcting an image in color, saturation or contrast you reduce the color information by 1 or more bits. If you start with 8 bits you might end up having only 6 bits real color information per channel. This loss can be seen in less smooth color gradients. If you start with 12 bits there is still enough color information available.

Also sharpening in 8 bits has the tendency to amplify the noise stronger than proper 16 bit sharpening (Photoshop got 16 bit sharpening in version 6.0)

 
Tip: Stay as long as possible in the 16 bit mode or even change to 16 bits/channel for stronger changes.
 

But why would you ever use 8 bits/channel if it is so much better?

  • It takes longer
  • Needs more memory
  • Creates larger files
  • Many Photoshop operations (e.g. layers) are not available for 16 bits/channel
 
9.3.12 Saving in different formats
 

Photoshop allows you to save your work in many different formats. Stay as much as you can with TIFF (8/16 bits) or use the PSD files for intermediate files.

Reserve JPGs for web work or sending images to friends.

 
 
9.3.13 Printing
 

Because of the color management features built into it Photoshop is also a print processor of choice for fine art photography.

The support for printing multiple images on one sheet of paper is pretty primitive.

We get back to printing in our chapter "Printing".

 
9.3.14 Perspective Correction and Rotating
 
    
 
Photoshop allows you to correct the perspective. You find some instructions in our primer.
 
We also have sometimes photos off level (Uwe more often than Bettina). We correct these faults also by using a transformation command ('rotate').
 
Unfortunately these tools only work in 8-bit. That is why you need to perform these transformation later during your workflow (after all the steps you can do in 16-bit).
 
 
 
9.5 Selected Photoshop tools
 
This section only looks at some Photoshop third party tools we would not like to miss. You can also find a lot of information in the Digital Outback Photo section "Photoshop Corner".
 
 
9.5.1 Plug-ins
 

9.5.1.1 Selective Color Corrections: Color Mechanic

 
 
 
9.5.1.2 Removing Color casts: iCorrect Editlab
 
iCorrect Editlab by Pictographics is mainly used by us for sophisticated cast removal. You can find a review by Jim Collum here.
 
9.5.1.3 Sharpening: EasyS
 
Our best sharopening tool so far.
 
9.5.1.4 Resizing
 
Genuine Fractals is the standard tool for file upsizing. Some swear on it and other think they have better solutions. We will discuss upsizing later in the printing chapter.
 
9.5.1.4 PowerRetouche
 

We like the PowerRetouche filters by Jan Esman which are mostly 16 bit. We regularly use:

  • Sharpness (not very fast but with very little sharpening halo and so worth the wait)
  • ColorRetouche (WB filters which uses terms of photographic filters)
  • Lens corrector
 
9.5.2 Techniques
 
9.5.2.1 Contrast Masking
 
There is often the situation that the shadows are too dark and the highlight to bright. Here a technique called contrast masking can help. We have a short tutorial here.
 
 
 
9.5.2.2 Moire removal
 

Some cameras like the Nikon D1x, Canon 1D or Kodak 760 produce some color aliasing (small colored pixels in the photo). We remove this the following way (works in 16 bits).

  • Convert to LAB mode
  • Select both A&B channel

  • Use the Dust & Scratches filter (radius 3-7 are good values)

  • Convert back to RGB
 
1.3.3 Actions by Fred Miranda
 
The actions by Fred Miranda deserve a special mentioning as they allow you to get sophisticated Photoshop operations and still be able to use them easily (see references)
 
References
 
Digital Outback Photo: Photoshop Corner
 
 
 
© Bettina & Uwe Steinmueller
 
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