Post processing refers to the editing done after a shot has been taken. In SLR cameras, there are usually two formats you can shoot in - RAW and JPEG. Raw files are unprocessed images recorded as the sensor sees it. JPEG, depending on your settings, has already been post processed to some extent. This can include sharpening, saturation, noise reduction, etc. The only problem with this is that the camera doesn't always process to a result you want, and this is where post processing comes into play by you. This guide will deal with how I work with the majority of my files: JPEG with little to no camera post processing.
Contents
1. JPEG vs RAW
2. Why Post Process?
3. Levels
4. Saturation
5. Sharpening
6. Black and White
7. Creating Frames Easily
1. JPEG vs RAW
RAW is essentially a digital equivalent to film negatives. It gives you the most flexibility when you need it. However, RAW files are much larger than their JPEG counterparts and will take longer to process and convert to other formats. For this reason, I would use RAW for specific occasions like shooting in very difficult lighting, or at an event I am paid for, where quality is of the utmost importance.
For the other 99% of the time, I shoot in JPEG fine compression with neutral saturation, normal sharpness settings, and noise reduction turned OFF. This gives me the best picture to work off and ensures the camera doesn't do any unwanted post processing to my pictures.
Of course, some people have their settings adjusted on their camera to suit their shooting style and preferences so that they don't have to post process at all. This guide however, will take you through the steps I take to make my images that much more vibrant and eye-catching. The steps I take are explained for Photoshop CS2 but equivalent tools can be found in most other good image editing software.
Before I start, I would like to clarify the definition of 'post processing' as used in this guide. Post processing is different to photo manipulation or editing where I add in another tree here or turn the sky orange. The purpose of post processing is to make an already well composed shot look better. It does not turn a bad composition into a work of art.
Usually, I take photos that are slightly underexposed. This makes sure that there are no blown highlights. Blown highlights are areas that overexposed to a point where the pixels are pure white (Red, Green, and Blue values are 255, 255, 255). In JPEG format, that information is not recoverable. It is easy to bring up detail in darker areas but impossible to get information from blown highlights. Shooting slightly underexposed images and then post processing to correct exposure is recommended for scenes with high contrast.
NB: Please note that blown highlights are perfectly fine when a photo calls for it. They can add dramatic depth to an image. It is when highlights are blown in crucial areas (like the focus point of the subject) that it causes problems.
Adjusting levels is the most easiest and versatile way to correct an image's exposure. Not only that, it also affects contrast and brightness which means you don't have to use separate tools and do almost everything in one go. Before I start, it is important to understand the levels curve and what the graph actually means.
Referring to the graph above, darker pixels are represented to the left, lighter pixels to the right. The height represents the amount of pixels.
The leftmost slider represents pixels that are pure black (RGB values of 0,0,0) while the right slider represents pixels that are pure white (255,255,255). The slider at the very bottom represents how black the blackest pixel can be or how white the whitest pixel can be.
If you look carefully at the left most slider, you will notice a tiny spike, which means that there are some pixels that are pure black. On the right side, you will see that there are no pixels that are pure white. What happens when we move the sliders?
See where the sliders are at now? Moving the black closer means that there are now quite a high number of pixels that are pure black (which you can see in the picture). The right slider shows that we have forced quite a few pixels to all-white. The water and the shadows in the rocks both have no detail in them, but the overall picture has gained a fair amount of contrast.
When you take a look at the graph again after applying the adjustment, you will notice white stripes. Photoshop was forced to redistribute the pixels across the scale. The white gaps means that there are no pixels of that particular shade in the image anymore, because they had to be redistributed.
if you get a levels graph that looks something like above, you should aim to move the right slider towards the left to just where you start to see the black line. This is because the light side of the image has absolutely no pixels in it at all, so why not distribute the pixels along the histogram more evenly to get a larger lighting range!
In Photoshop, you can use Image > Adjustments > Levels to play with this setting. A basic summary of what you will achieve by adjusting which slider is as follows:
Saturating an image to make the colours more vivid and vibrant is easy to do, however the problem lies with knowing which images should have increased saturation and which need to be left alone. For example the images below shows how useless saturation is in this case.
As you can see, the difference is barely noticeable as the original image has colours that are already fairly saturated. It makes a perfectly fine photo as is, and there is no need to fiddle with the colours here. In fact, doing so will only reduce the amount of detail the original image had, as increasing saturation might force colours that are near their maximum colour value into the maximum value meaning that any small changes in shades will be lost. Other images however, will benefit greatly from a saturation boost.
While the original image looks fine as it is, boosting the saturation draws focus to the contrasting colours in this image. All of a sudden, you notice the contrast between the lady beetle's spots and the stripes that is pictured with.
In Photoshop, you can use Image > Adjustments > Hue/Saturation to adjust the saturation. Hue should be left alone as changing the colours of an image to a different hue borders on photo manipulation, as opposed to post processing.
This is one of the most important tools that you should learn to use and use well. Sharpening an image is a good way of making images appear more detailed and crisp, however, many people use it incorrectly by overshapening images. This is easily spotted and looks horrible! If someone can tell that you have used a sharpening filter on your images, then it is very poor processing on your behalf!
The best tool to use for sharpening an image is the 'Unsharp Mask' filter (USM). I won't go into details, just know that a blurring of the image occurs somewhere in this magical process, and thus the term 'unsharp mask'. You should know this much though: it works by increasing the contrast (light and dark) of all the edges in the picture. By doing this, you're eyes are fooled into thinking it is a more detailed image, when all that is really happening is that the edges of details in the image have more contrast to each other.
You can access it in Photoshop by going to
( Filter > Sharpen > Unsharp Mask...) and you will see settings like this:
Here's an explanation of what these sliders do in terms of the difference you'll see (and not the technical side of it):
Amount is essentially how much more contrasted the edges will be. You need to be careful with this setting as too much will create a halo around all the edges in the image. This is the number one mistake people make - a halo is the most prominent sign of oversharpening.
Radius is how wide the edges will be for this contrast change. This setting the most important for getting the result you want. Just remember this - if the image you are sharpening is a large image (as in straight from the camera, not resized), you will need to use a larger Radius setting so the filter can be applied to a thicker edge size. It is different for all images but a guide is perhaps 2 pixels. If you are working with smaller images, such as images that are 800x600 pixels or less, then use smaller Radius sizes, around 0.5-1 pixels. Using a pixel size that is too large will result in what appears to be 'colour bleeding', when in fact the contrasted edges are simply being taken from a wider sample than is required, causing parts of the images that are not edges to change in colour.
Threshold tells the filter what it should define as an edge and what it shouldn't. Increasing the threshold tells the filter to sharpen only very defined edges, the more you increase it, the more selective it gets. If you have a grainy image for example, setting the Threshold to 0 will mean that the filter might treat each grain as an edge, increasing its contrast and thus making the image even grainier. Moving the threshold up a little will get the filter to ignore the grain (if it is not too pronounced), and only sharpen very defined edges.
Below is are three images showing what a properly sharpened image could look like from the original, and also what oversharpening looks like.
Many people use the easiest way to make a picture black and white, and that is by desaturating it (or grayscaling it which is better but still not the best). While this is a quick method and sometimes produces good results, it is not the best way to go about it. The three images below show respectively an original, after it has been desaturated, and the method you will learn here - using the Lightness channel in Lab colour.
Take a close look at the differences between the desaturation and the Lab colour method. You will notice that the crane is very white in the latter, not to mention that the ninja star has much more contrasting shades. Also with the lab colour method, blacks are blacker and the rendition as a whole is a lot closer to the results you would get with traditional black and white photography on film.
The reasoning behind how these two works is as follows. Desaturation uses the strength of each colour to determine how black or white a pixel should be, and strips out all the colour. The resulting image has shades very similar to the original but without colour. The lab colour method is rendered based on the amount of reflected light a colour would have. You'll notice that the crane, for example, is quite a light colour and would reflect a fair amount of light in real life. It is correctly represented using the lab method.
- How it is done: In Photoshop, change the Image Mode to Lab colour (Image > Mode > Lab color)
- Next, open up the Channels palette
(Windows > Channels) - Select the 'Lightness' channel and notice your image changing
- This is the time to apply any level adjustments you need to get the contrast you are looking for.
- When you are finished, finalize the output by choosing Grayscale mode, and 'yes' to the 'Discard layers?' dialogue
(Image > Mode > Grayscale)
That's it! There are many more ways to make an image black and white, but the method above is the easiest way to get great results.
Frames are an essential part of a photograph, whether it be one displayed on a wall or digitally on the internet. A simple frame will eliminate any distractions and make it easier for the eyes to focus only on the image, the way all good photos deserve to be viewed.
I will explain how to easily create frames using Photoshop Actions, which will save time if you have many photos you want to frame for displaying on the internet.
You can create a variety of simple frames using Actions by following the steps below. It will show you how to create frame that consists of a thin black, thin white, then thick black frame (which I like the most). You can adapt and design your own after you understand how it works!
- Before you start, open up your image and have it at the stage where all you need it to be is framed. You need to have an image you want to frame already open before continuing
- The next step is to open the Actions palette
(Window > Actions) or use the shortcut Alt+F9 - You will notice a little arrow pointing right, in the top right corner of this window. Click on it and then select 'New Action...'
OR, you can click on the little "New action" at the bottom of the actions pallete
- Enter the name of the Action, e.g. 'Thick photo frame', and then select a function key you want to use as a shortcut to execute this Action. Let's use F12. Select F12 from the drop-down box and check 'Ctrl'. This means your frame will be created when you press 'Ctrl+F12'. Leave everything else as is and click 'Record'
- Now select 'Canvas Size...'
(Image > Canvas Size...)
and fill in the settings so they look like below
- A black border is now added to your image. Repeat step 4, but this time change the pixel width and height to '2' pixels and the background to the colour 'white'. Then click Apply
- A thinner white border is now added to your image. Repeat step 4 one last time, but this time change the pixel width and height to '20' pixels and the background colour to 'black'. Click Apply. You should now have a border that looks something like this:
- Finally click on the 'Stop Recording' button at the bottom of the Actions window (marked by the red box below)
That's it! Now, every time you want to make this border for any photo, just press Ctrl+F12. You can create different borders and put them under different shortcuts. Experiment with the amount of borders, the size and the colour to suit your tastes.
SOURCE
technorati tags:photography, raw, post-process, levels, saturation, sharpening, BW, frames
No comments:
Post a Comment