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Post-Processing Part 2: Editing Images


In this section we are going to cover the basic editing you might do to any picture, whatever the subject.
Select an image from your library and double click to open the editor panel.
On the left hand side you will see the basic correction options you have available.



Cropping an image is one of the most basic, but most powerful things you can do to an image to improve it.  You can use the crop tool to remove unwanted background details and focus in on your main subject.

Click on the "Crop" button to view the details or the crop tool.  "Manual" allows you to draw your own crop rectangle.  Or you can select standard crop sizes - for example Square or A4 to fit particular formats.
In Manual mode you just drag the mouse over your image to select the area you want to crop to.   You can adjust the size by dragging on the edges or corners of the crop rectangle.   You can adjust the position by dragging the mouse within the crop rectangle.
Once you have it how you want it just click "apply".



The straighten tool allows you to rotate the image to make verticals or horizons lie properly in the frame.  You can also put a tilt into an image if you want.
Notice that as you tilt the image that picture "zooms in".   The rotation has to apply some measure of cropping otherwise you would get borders in the corner of the image.

Auto Corrections


The name comes from the Google search option "I'm feeling lucky".   This option does an automatic correction on an image.  It adjusts contrast, colour and exposure for a "best" fit.
Auto-contrast and auto-colour do the same but for only the selected options.

Fill Light


Fill light lets you add brightness into the darker areas. It brightens the image overall, but the greatest effect is in dark tones with a very minimal effect in light tones.

This original image is very dark in the background.

Using the fill light slider has boosted the brightness in all the dark areas.



Red-eye automatically finds red eyes (caused by flash light bouncing off the retina of the subject). It then removes the red from the eyes.

The green highlights indicate where Picasa thinks the eyes are, ready for removing the red tone.



The retouch tool is basically a spot-healer - although it can also be used for removing dust and dirt from an image. With an image shown at full screen it can often be difficult to see the blemishes you want to remove. Zoom in to a more magnified image by turning your mouse scroll wheel or using the magnify control at the bottom of the screen.

Move the cursor over the blemish you want to remove.  Click once to see a preview of the correction, and then click again to make the removal final.   Continue doing this over the image until everything is clear.
Click the Apply button when you are happy with all the spot removals in one go.

Advanced Exposure Correction


Clicking on the brightness icon opens a new panel where you control exposure of an image in a more detailed and manual process than just using the automated tools.  Firstly we have a repeat of the fill-light tool discussed earlier.
Then we have separate controls for the highlights and shadows.

Dragging the highlights control to the right brightens the brighter parts of the image, leaving the darker parts barely changed.

Dragging the shadows control to the right darkens shadow areas with a minimal change in bright areas.

Colour Correction


Dragging the Colour Temperature slider to the left adds more blue.

Dragging the Colour Temperature slider to the right adds more yellow.

You can also select the eye-dropper tool and then click on a part of the image you know should be a clear white or grey. Picasa will calculate the overall colour temperature change required to bring your selected colour to be a neutral grey or white tone.

Basic Effects


Clicking on the "Fun and Useful Image Processing" tab opens up a small panel with a range of quite useful options.

SHARPEN will refine the image to look crisper - it is not a fix for an out of focus image, but does add a little more definition to the image. One of the most common faults I see in photographs is the over use of this control.

SEPIA, B&W and WARMIFY are a selection of simple filters to set for example a basic sepia look.  You can click on several of these at one time, or indeed the same one several times for a stronger effect.

FILM GRAIN adds a crude grittiness to an image, slightly reminiscent of film photographs.

TINT sets an overall colour tint to an image. Use the slider to fade down the strength of the tint so it is not so "in your face".

SATURATION gives a colour boost to the image. This brings up the strength of any colour found, but leaves neutral tones alone.

SOFT FOCUS is a three part control.  Firstly the cross hairs indicate the part of the image which remains unchanged.  Secondly the "size" slider determines how larger an area remains unchanged.  Thirdly the "amount" slider adjusts the amount of soft focus to be applied.  Use with care this can add a nice gentle effect to a portrait or even landscape.

GLOW is a variation of the soft focus theme - again terrific for portraits. Glow basically adds a soft brightness increase around brighter parts of the image. This has the general effect of softening and smoothing as well as adding a hint of glamour. A good tool for feminine portraits.

FILTERED B&W creates a black and white image - as though it is seen through a colour filter. For example a RED filter will tend to look better on skin tones, since it has the effect of removing blemishes and wrinkles. A GREEN filter might be used on a landscape to boost definition in leaves.

FOCAL B&W changes most of the image to black and white except for your focussed area. It works in the same way as the soft focus tool in terms of controls. It allows you to maintain colour in one area to highlight that part of the image.

GRADUATED TINT applies a colour (or grey tone) to the top of the image. You control how deep the colour is and how soft the transition between the coloured and clear area. Most useful on a landscape type image where you want to put some colour into a lifeless sky.

Additional Options


There are lots more fun options to explore, some of them more useful than others.
To speed up working on many images you can also apply certain options as batch process across a collection of images.  So for example if you have the same colour temperature or brightness flaws you can fix them all in go.
You can also copy and paste the treatments from one image to another.

Advanced Software Options


This guide to Picasa is a really good lead-in to the options you have available in any software package. In general the more sophisticated the package the greater control you have over adjustments. However there is also an increased learning curve for advanced tools and I won't tell that you Photoshop is easy. I've spent years using the tools and I still find new methods and techniques, apart from the additional features and improvements being released all the time.



Now it is time to go back to your favourite images and decide how you can use any of the correction tools or special effects to improve on them.
Look at both details (minor exposure correction, blemish removal) and the whole image (conversion to black and white or colour tinting).
Avoid using the special effects for the sake of it - while they may be new to you there are plenty who have seen far too much of them.  Instead try and find effects that genuinely enhance an image.