Simple Image Editing, Cropping Suggestions
Key Vocabulary to Remember
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Introduction
Image editing aims to achieve the best results from your initial captures. The most effective approach is to select what part of the picture best conveys your message. Cutting the less interesting parts from the picture may offer a more meaningful end result. In this way there is less of a requirement for image processing and editing to emphasize the subject.
There are also other ways in which an image can be adapted for publishing. Creating images that have the same aspect ratio, or proportion of width to height dimensions, ensures a consistent look that is well suited for websites and other similar processing tasks. Resizing a picture, ending with one that has less resolution, can be highly suitable to fit within the constraints of size imposed on various formats.
The final option for editing is to apply various effects such as adding transparency, colour and image processing algorithms that alter the initial image to fit various esthetic requirements. Editing is highly personalized, depends on talent and has complex goals, going beyond the scope of this document. There are very good tutorials and examples available on the internet that showcase very good techniques.
The operation you will most likely carry out, and almost on your first photographs, is cropping, or selecting which part of the original should be kept and put in emphasis. Whole pictures can happen and are appreciated. Most of the time, however, you can create better photos out of your original ones and it is great to experiment.
Cropping
The most simple and effective way to vastly improve the attraction of any picture is to have a very good framing of the picture. Even for very good captures, it is likely that there are elements which detract from the atmosphere that you want to convey. Sudden highlights, the presence of certain high detail objects or individuals close to the edge of the picture frame may detract from the focus you want to have. To counteract this limitation, cropping the edges of the picture is highly useful.
Cropping a picture may end up with different results. Each subsequent crop has to be analyzed side by side with the initial one, and compare cropped versions with each other in order to decide the most suitable photo. This goal can be achieved in free PC image editing software such as Gimp, Paint.Net, Krita. Certain publishing platforms such as Facebook and Instagram integrate on-the fly cropping in the image uploading interface, leading to great creative capabilities on all photos that do not require using the previous mentioned software. The ability to preview the image before publishing is highly valuable. As image sharing websites are already created to accommodate pictures from various sources, there are no concerns about inconsistent cropping between different pictures as the platforms has a good control on how it frames such pictures to maintain the intended look.
For websites, video editing, desktop publishing, cropping is best left as the final stage of composition, carried out in the main program and not on image editors. Keeping the unedited picture as long as possible improves the prospect of reaching high quality results. Any subsequent editing reduces the picture quality and permanently affects the outputs in ways that may not be easily overcome.
Cropping discards a part of the picture, reducing resolution and potentially affecting the image aspect ratio, if the edited area is unevenly distributed on the horizontal and vertical side. Most modern websites work well if the aspect ratio is maintained, but some require the same resolution, as they do not carry out this process. Resizing an already cropped picture leads to less quality than the original one.
What is the aspect ratio
The aspect ratio, as the name implies, is a proportional relation between the horizontal and vertical dimensions of an image. Depending on the source of your image, you may have widescreen, square or narrow images. Most cameras, including the ones on smartphones, create pictures that are typically widescreen, when used on the landscape orientation. If the orientation is, instead, placed at 90 degrees, you end up with portrait images, that are much taller and narrower as well.
Note that depending on the camera being used, the format that is preset on the camera and other conditions, you will end up with widescreen images. However, note that widescreen images are not necessarily having the exact same aspect ratio although they may look similar.
To express the aspect ratio of an image, you divide the width of the image to its height, measured in pixels or inches/centimeters, if you have actual physical creations. For a typical photography or video clip, the aspect ratio is typically 16:9 and it is derived by dividing a resolution of 1920 to 1080. Then, the resulting value of around 1.78, which is what dividing 16 to 9 would result in. Note that you can also simplify your 1920 to 1080 division and you would end up with the same integer values that cannot be further simplified, 16 and 9.
It is advisable to get used to thinking about your pictures also in terms of their aspect ratios, whether you actively use these estimations for editing or not. In this way you have a better perspective of what formats you work with and get used to different techniques of editing.
Common aspect ratios
Many years ago, since 1950s and until the early 2000s, the 4:3 aspect ratio of PC displays and TV screens was very popular. In the late 2000s, such formats were superseded by the so-called widescreen one, 16:9, used in the film or movie industry. As a result of this transition, just about any camera, professional or consumer, as well as most displays, generally create images that are suitable for this purpose.
Having a common aspect ratio simplifies content creation and editing but leads to issues when such formats must be exchanged, as there is no straightforward or easy way in which images can be changed from one aspect ratio to another. Such post-processing techniques require advanced image editors to reach adequate results. For video production, editing is even more difficult and time consuming than for individual photographs although, if you commonly edit many pictures, it can be tiring.
Using the aspect ratio required by your publishing platform is simple and effective but it limits how you work with your photographs. It is better to use various aspect ratios, as needed. However, if you do not have specific requirements, using the typical widescreen format of 16:9 is a good start.
Aspect ratio adjustments
Certain publishing formats, such as websites, may benefit from images that are particularly edited to suit a graphics theme. As most websites are created for the typical laptop screen, this means that a landscape or 16:9 format is targeted. Since initial photos can have any resolution and aspect ratio, simple editing may be required prior to publishing. Most editing software can superimpose a freely movable, white edged cropping area on the original image that can be moved freely, showing visual cues that help decide which crop is most suitable. After applying the process, a resulting image is created.
Transforming an image from one ratio to another is not straightforward and, actually, distorts the picture. Since you cannot do otherwise than stretch the image or compress it to reach the new format, results will be poor with simple approaches of just specifying a new resolution that fits your requirements and respects the aspect ratio you target. The best approach is to use semi-automated means of cropping the picture with an imaginary rectangle, selecting what should be preserved of the original photography. In this way, no distortions are created.
Nowadays, 16:9, or the widescreen format is the most popular one but keep in mind that anything else but a TV, most display, projectors, require a different aspect ratio. Sometimes your platform will adjust your image, at other times you have to process the image yourself. It is advisable to experiment with different aspect ratios.
Flipping (Mirroring), Rotation
Flipping, mirroring and rotation are highly common editing operations required to either correct images or make them usable in specific contexts. Most simple operations can be applied without affecting the original file. The only exception is when carrying out non perpendicular rotations or rotations at other angles than 90 degrees.
Your pictures may need to be flipped vertically or horizontally when you want to show a different position of your subject or show a different scene arrangement. Flipping refers to a change around the imaginary axis of your photo. A horizontal flip ends up with a picture that has the upper and lower side switched while a vertical one ends up with a similar effect, but having the left and right side switched.
Rotations are highly useful operations that are applied to correct the way in which an image is shown, to use a specific part of an image better in another composition or to straighten the image slightly. The most common rotations are in increment of 90 degrees. Such a rotation ends up with a horizontal image being shown vertically or a vertical one shown horizontally. This is highly useful when you need to emphasize a specific part of an image and use it another composition. Considering you still have enough pixels left on the axis on which your picture is required to be very wide, you can successfully make a later crop and end up with a good result. Rotations at 180 and 270 degrees are useful in specific circumstances such as when you want to alter also the orientation of the image more than a simple clockwise or counterclockwise operation would achieve.
Adjustable angle rotation can be applied on all pictures in more advanced image editing software. However, you should always keep in mind that straightening a picture may require values of less than 5 degrees deviation and they have to be individually determined through trial and error. Unless severe, most slight tilts in photos are not noticeable. Attempting to edit them requires dedicated time and may only be justifiable for professional activities. Always expect that after a rotation you may need to apply a subsequent crop and discard more of your picture areas that were added by the rotation algorithm to end up with the same format as the initial image. Unless experimenting or for strong reasoned cases, minor angle adjustments are not recommended.
For smartphones it is highly useful to correct a wrong orientation hint by a simple editing in any program, as it avoids the unpleasant aspect of an image that is presented horizontally or vertically instead of the other way around. From time to time, and particularly with less swift movements, you may end up with an image that has the wrong orientation indicated int the file, and as more software takes into account this hinting you may need to correct orientation.
Always experiment with flipping and rotation, particularly early on, to develop a photography perspective. 90degree rotation and flipping operations do not affect the image quality in any way, including for JPEGs, as software algorithms evolved to directly apply such operations without saving a re-compressed image afterwards
Light, colour, contrast adjustments
Ideally, your image should have the best brightness, contrast and colour aspect. Unfortunately, it frequently occurs that some processing is required to show particular images in the best way. This requires processing in dedicated image editors, whether free such as Gimp, Krita, or paid, as Adobe Photoshop. Simple processing is best used with non-commercial applications as such operations do not require expensive software and it is better to be aware of general editing principles rather than a single approach to fixing.
Keep processing to a minimum and use sparingly brightness and contrast adjustments. If your software has auto settings, try to use them for quick results that do not end in hard to understand solutions. Experiment as much as possible with different settings to improve your skills and learn to compensate for your camera's shortcomings
Brightness adjustments
Keep in mind that it is always less suitable to post process pictures than to have good ones from the start. Most pictures will probably end up underexposed, or darker than they should. This requires an auto-brightness adjustment or a manual one, applied with care to not leave any part of the picture overblown or unrealistically bright. On too bright or washed-out pictures, you reduce the brightness slightly to reduce the impact of too harsh light cast on different areas.
The most likely operation is brightness adjustments, most likely in an attempt to lighten rather than darken an image. Make small adsjustments and evaluate carefully the before and after effects. Always keep the original image for reference and future use.
Contrast adjustments
It is advisable to control brightness and contrast at the same time, and try to increase contrast slightly when making editing. Keep in mind that too much contrast accentuates in a unrealistic way the picture and it is not preferable. Slightly increasing contrast and light by low amounts, in the range of 5-10% generally ends up with slightly more appealing pictures. To have a good grasp of the result, always compare your initial picture with the resulting one at different values, and note which one ends up with the best compromise.
Contrast adjustment can artificially make a picture more appealing while it can also lead to an artificial look if overdone. Adjust as little as possible contrast or leave it unchanged to avoid loosing more subtle details in your picture.
Saturation adjustments
Saturation adjustments are even more difficult to carry and more subjective. As a rule of thumb, you avoid overly bright or intense colours or ones that are way too subdued. However, always take note that increasing saturation also increases the chance of various artifacts and unwanted parts of the picture to stick out much more than you would like. This is why saturation should be generally left as is. As a rule of thumb, when increasing brightness in a picture, you can slightly bump saturation by a few percents to avoid an overly drab image.
Colour adjustments are rarely needed unless you want to emphasize your subject or reveal other aspects. Try to avoid more than subtle adjustments as it can easily result in an unsavory picture.
Tone or white balance adjustments
In much less frequent situations, you may need to resort to tone or white balance adjustments. This might be the case when using indoor light cast towards your subject. As the light level is already low and the light source itself has a colour spectrum that is optimal to the human eye, it may look entirely different to your camera. If you cannot increase enough the light levels and you need to make snapshots in this condition, always expect post-processing operations in your image editing software.
The purpose of tone or white balance adjustments is to simulate a more balanced colour appearance, particularly when having a white element in your scene. When such elements can be spotted, it is expected to have a proper colour balance. Applying an automatic colour balance can generally work very well. If you do not have an automatic white balance feature in your graphics editing suite, you can probably aim for a 5500 Kelvin one, as a good compromise, unless you really want to emphasize warm tones. Try different combinations until you end up with a white element that is neither too yellowish or blueish.
Except on indoor scenes and very low light situations, you rarely need white balance adjustments or processing. When you do require such operations, it is great to know what you can do in advance, to save time on subsequent activities. All white balance issues can generally be solved, at the slight expense of reduced colour saturation.
Brightness adjustments
Complex effects
Complex effects may be applied to images and result in interesting effects but keep in mind that some effects can be effective enough when used reasonably. Generally aim for edits that affect an image the least but can create a very good effect. Flipping images horizontally or vertically, mirroring them, rotating them at right angles such as 90 degrees or 270 degrees, can result in images that are surprising to your audience. Rotating pictures at arbitrary angles may be less straightforward, as it requires additional cropping to end up with usable pictures. However, such operations may be useful when you want to straighten an image or show a different perspective on the subject.
Image flipping and rotation, with a potential subsequent cropping, is a good approach to end up with different photographs that present the perspective you want. It is always advisable to experiment with all sorts of effects and analyze the original to processed edits, by yourself or along others, for better feedback.