Composition in Landscape Photography - Pleasing the Viewer's Eye

Beautiful subjects and technical ability are not enough to make a good picture. Photographers must properly compose the photo, too. Composition should be pleasing and harmonious; it should help driving the viewer's eye through our picture as we desire. Elements to consider for an attractive composition are dominant feature, balance and rhythm.

Beauty is in the eye of the beholder. A composition looking harmonious to a person might look lackluster to another. So feel free to adapt the suggestions in this article to your needs and attitudes. Besides, try your best not to be stuck into rules and commandments, because they might be the loss of your creativity. Remember: photography is the art of seeing, not the skill of following the rules. Seeing things differently might convey different composing, which is good, because original and personal. Experiment with your creativity and inspiration; try breaking purposely the rules. This means that occasionally you will have to throw away a few shots and this is good, too. Indeed, if you have seldom some shots to dismiss, it means you are not experimenting enough. Having said that, let us list a few concepts we should refine our sensitivity for.

Main Subject

It should be self-evident that before shooting we should know exactly what our main subject is. We must do our best to convey the viewer's attention to it, without distracting elements. This does not mean that we must exclude everything except the dominant feature in our image. In fact, we have three options:
1) Macro-photography. Show only the main subject and nothing else. This yields the advantage of no distractions to the viewer.
2) Intimate landscape. Show the main subject together with its neighborhoods to give it a spatial placing. This can be useful to make it easier to recognize the subject or to say something more about it.
3) Grand scenic. Show the subject immersed in its entire surrounding. This can be done if the surrounding is meaningful to the feelings you want to convey.

In any case, the viewer's attention must be attracted to the main subject first, and only then he can wander around the rest of the picture. If the viewer's eye does not go directly to the main subject as soon as he looks at the picture, the photographer has failed his mission.

Here are a few useful tips in order to emphasize the dominant feature. Put your main subject in the foreground so that it appears bigger. Typically, this requires a large depth of field. Another popular method is using converging lines toward the subject to direct the viewer's eye where we want to. Putting the dominant feature against a contrasting colored background is effective, too. For instance, the main subject could be a splash of color against a complementary colored backdrop. Finally, a shape with a textureless background will serve the purpose of making the main subject figuring prominently. An example of this might be a flower in the desert sand.

Balance

In a photograph, more than one object or person is usually present. Each item in an image must be properly balanced. A balanced composition is pleasing to the eye because inspiring a sense of stability. Each item has a weight or visual importance that depends on the level of attraction for the viewer's eye.

Balance can be symmetric or asymmetric. In asymmetric balance, a small object is balanced by another bigger having more or less the same visual importance. For instance, this is the case when a small highly colored or contrasted object is related to a bigger but plain or textureless item.

Rhythm

Rhythm relates to time and it implies adding the time dimension to photographs. As we saw, the viewer should be first attracted to the main subject, but then there are other (well-balanced) items in the picture he should look at. The photographer should be able to take the viewer in a journey, to involve him in the image. The journey begins with the main subject, and then the viewer should be led to the rest of the picture smoothly and with participation, along items of secondary importance. Think about this imaginary journey and try to compose it in your picture so that the viewer will be delighted to follow you and to go all over the path of your vision.



By Andrea Ghilardelli



Andrea Ghilardelli runs a photo retouching and restoration service at ilghila.com.

Perspective - Sense of Depth in Photography

Perspective is a part of geometry teaching how to render a three-dimensional figure on a two-dimensional surface, so that, looking at the representation, we have the same impression that we have with the real figure. Therefore, it is easy to see that perspective is very important in photography. This is particularly true in landscape photography. A photographer should know how perspective works and how to exploit it to render reality as he or she desires.

Simply stated, perspective relies on two fundamental rules:

1) The nearer the object, the bigger it appears.
2) Parallel lines seem to converge toward a point.

Our brain relies on these two tenets to perceive depth and distance. So, getting down to the nitty-gritty, if a photographer wants to create a conspicuous sense of depth, he should make the above-mentioned rules evident. On the contrary, if his aim is to make a picture look flat, he should minimize these two perspective effects.

Let us assume we want to produce a strong sense of depth. We can achieve our goal by inserting in our picture a few converging lines. The more converging, the more intense the sensation of depth. Alternatively, or together with it, we can put an object in the near foreground and a far background behind. The object in the foreground will appear bigger compared to the background and, again, this will improve our impression of depth. The nearer the object in the foreground, the higher the perception of depth. For instance, when shooting a landscape picture, have some flowers in the foreground and the panorama behind. On the other hand, if a photographer would like to make a picture look flat, he should remove any object in the foreground or step back from it so as to render it less conspicuous.

Be careful when getting closer to an object in the foreground, however, as it may get out of focus. Always keep an eye on the depth of focus of your camera and lens system when taking a picture. Both the foreground and the background should be in focus, unless a blur effect is intentional. So choose the aperture of your camera accordingly.

If you happen often to take landscape pictures and then, when looking at them, realize that they do not convey the same feelings as reality, sometimes it may be because of lack of depth. Try applying the rules in this article to give your two-dimensional images a better illusion of depth.


By Andrea Ghilardelli


More articles about photography at ilghila.com.

ISO Setting in Digital Cameras

What happens when we select a certain ISO value in our digital camera? What is the best ISO setting for our particular camera? Can we change it light-heartedly or does it deserve a more careful consideration? Read on to learn how we can improve our photographs through the right selection of the ISO setting.

Let me give you the bad news, first. Camera manufactures do not disclose strategic and sensitive information such as what happens internally when the user select a certain ISO value. Anyway, through sound reasoning and a little of reverse engineering we can speculate on it and come to meaningful conclusions. In particular, reverse engineering is best performed on RAW file format, rather than JPEG, because JPEG compression introduces artifacts and algorithms complicating the process.

For starters, we need a definition. Image sensors have a so-called native sensitivity. This is the innate or natural sensitivity of the sensor when compared to a standard film. For instance, if the native sensitivity of a certain sensor is 100 ISO, it means that it gives comparable results to a 100 ISO rated film when both are used at the same aperture and shutter speed. Native sensitivity cannot be changed, because it is inherent to a certain sensor. Therefore, when we change the ISO speed setting, something must occur involving the circuitry serving the photosensitive sensor. More specifically, things play out differently according to whether an ISO greater or lower than the native sensitivity is selected. Let us see the two cases separately.

ISO setting > native sensitivity

We must know that the electronic charge created inside the photosensitive array of the image sensor is first sensed and transformed into an analog voltage by an amplifier and then an analog to digital converter (ADC) transforms this voltage into a digital number. The amplifier transforming the electronic charge into an analog voltage has a certain gain, meaning that to a given input corresponds a certain amplified output. Put mathematically:
output = gain * input
The greater the output, the brighter the image. When the photographer opts for an ISO speed greater than the native sensitivity, the gain of this amplifier is increased. That is, the microelectronic circuitry is designed to augment the gain of the amplifier. For instance, if the selected ISO is twice as much as the native sensitivity, the gain doubles. If the gain increases, then the output for a given input will be greater, thus leading up to a brighter photograph. Hence, the chain of events is the following. The photographer realizes that he is going to shoot a very dark scene, so he decides to select a high ISO setting. The photons hitting the sensor and thus leading to electron generation do not change, of course (i.e. the input is the same), but internally electronic charge is magnified by increasing the gain of the amplifier, as if the amplifier sensed a greater number of electrons. All this leads to a brighter image.

Unfortunately, this is not magic. As the signal is increased, leading to a brighter image, the noise is increased as well, leading to a noisier image. That is why we should be careful when increasing the ISO speed in subdued light conditions. Always do that when no other option is available (e.g. a tripod).

In some cases, a fiddling in RAW data may also occur to boost to very high ISO speed.

ISO setting < native sensitivity

If this is the case, then the camera’s circuitry adjusts the image data after the analog to digital converter, directly in the digitized form. For instance, if the selected ISO is half the native sensitivity, brightness values represented by each RGB channel are halved. This leads up to a darker photo.

This has a drawback, too. Indeed, a common ADC has 12 bits per RGB channel. When its numbers are halved, they can be represented by 11 bits (12-1). This means that the dynamic range is reduced and some information lost forever.

Conclusions

As we saw, drawbacks arise using an ISO setting both higher and lower than the native sensitivity. So, it is best to shoot at the sensor’s native ISO whenever possible. That said, unfortunately this is not a technical characteristic cameras’ manufacturers divulge. Consequently, you have two options to know the best ISO setting for your camera. The first one is to sift through the numerous forums on the web or, better yet, experiment by yourself with your specific camera.


by Andrea Ghilardelli


More articles about photography at ilghila.com.

Form in Landscape Photography - Lines, Shape and Volume

For a picture to look beautiful, many elements can concur. One of these elements is form. For a better understanding of what form is, imagine a black and white photograph. Without color, form is the prominent feature of the image. A classical example where form is the major constituent of a picture is the silhouette. Form can be thought of as the combination of three fundamental constituents. From the simplest to the most complex, they are lines, shapes and volume. Let us take a deeper insight to each of the three constituents of form and how to exploit them for composing better photos.

Lines

When composing a photo, take care of lines. Lines are defined by the juxtaposition of two regions with high contrast. Contrast can be determined both by differences in brightness and by diversity in colors. Lines serve two main purposes. The first one is to define shapes. The second, less trivial and most challenging, is to drive the viewer's eye where we want to. For instance, if you want to attract the viewer's attention to a certain subject, try having lines converging to that subject. On the contrary, if your aim is to have the viewer's eye wander throughout the picture, try having diagonal lines crossing it.

Preponderance of vertical lines gives the composition a vigorous touch. On the contrary, prevalence of horizontal lines suggests a sensation of quietness and balance. Diagonal lines usually give a dynamic feeling to the composition. Finally, curved lines can create rhythm, harmony and depth; they can also drive smoothly the viewer's eye around.

Shape

The second element of form in order of complexity is shape. Shapes are two-dimensional and, just like lines, their contrast depends on the juxtaposed regions. The above-mentioned silhouette is an effective example where shape is pivotal in an image. Inside shapes sometimes texture may be present. Texture is the structure and the appearance of something. It tends to make lines and shapes less noticeable. Repeating shapes build up a pattern.

Volume

Although a photograph is inherently two-dimensional, it can convey the sense of depth. When this happens, we have volume, i.e. a three-dimensional impression.

The best way to achieve this is by inserting elements in different planes in the image. For instance, a landscape photography picturing a panorama, will give a greater sensation of spatiality if a nearer element is present in the foreground, such as a shrub or a person. Another example might be the insertion of two identical subjects at different distance; they will be reproduced at different scales and will convey an impression of depth. Usually, the photographer must ensure that the elements giving the sense of depth be in focus. Technically this is accomplished by setting the depth of focus as high as possible. Sometimes you may even take advantage of the atmosphere to render depth, because the further the objects, the mistier they appear ("aerial perspective").



By Andrea Ghilardelli


More articles about photography at ilghila.com.

Complementary and Harmonious Colors

Mastering color is an essential ability to any good photographer. To achieve proficiency, a basic knowledge of primary colors and complementary colors is required. We will define these fundamental concepts and teach how to exploit them in order to take better photographs.

The great physicist James Maxwell in 1859 demonstrated that each color could be obtained starting from just three colored light beams, one red, one green and another blue. By over-projecting these three beams on a white screen and by carefully dosing their intensities, any color could be attained. This is the basis of the aptly named "additive synthesis". These three colors (red, green and blue, or RGB) are called "primary colors". Adding all the primary colors at their maximum intensities, give rise to white; black is the absence of any light.

Each primary color also has a "complementary color". The complementary color of a given primary color is defined as the color that added to the primary color gives the white light. It can be shown (but we will omit the demonstration) that the complementary colors for red, green and blue are cyan, magenta and yellow, respectively. What a photographer must always keep in mind are simply the (fundamental, complementary) color pairs:
(red, cyan)
(green, magenta)
(blue, yellow)

Masterful control of complementary colors is essential in composing an image. Juxtaposition of complementary colors always creates striking chromatic contrast. Consequently, if you wish to make an object stand out from its background, you should pick up a background with the complementary color of the object. Good examples are yellow autumn leaves against a blue sky or magenta flowers against green foliage. The main subject will immediately catch the attention of the viewer. It does not matter how small the main subject, if it has a complementary backdrop, will always be an important compositional element. Usually it will draw the whole attention.

Similar colors are harmonious and not complementary. When just harmonious colors are present in a picture, color is typically not the main attraction. Other fundamental elements take over, such as form and texture. An example might be green grass against a blue sky. Let me give you a tip: if you are going to take a shot of a green grass, back lighting will produce a fantastic effect, making the green very vivid and glowing. So, keep in mind that direction of sunlight is important, too. Be careful when making compositions with similar colors in black & white photography. Most of the time, what appears clear and well defined in the colored world, will seem confused and lackluster in black and white.

Now you know how to compose a highly contrasting image or, on the contrary, a harmonious picture. All of this from a chromatic point of view. Now it is time for the better thing you can do: experiment what you have just learnt.

By Andrea Ghilardelli

More articles about photography at ilghila.com.

Frame Transfer and Interline CCD - Electronic Shutter in CCDs

Image devices with a CCD sensor, such as digital cameras and camcorders, can readily implement an electronic shutter. Such electronic shutter does not require extra circuitry, because the way a standard CCD is operated already has an inherent shutter. However, if a fast shutter speed is required, the CCD integrated circuit must be enhanced in some way.

Full-frame CCD

The full-frame is a CCD in its simplest form. It is made of an array of photosensitive elements (pixels) where electrons are created by incoming photons from the time we press the shutter release button throughout the exposure time. Then a shifting phase occurs, shifting these electrons one row at a time to a sensing circuit producing a voltage proportional to the number of electrons. The shifting takes place as follows. The electrons of the first row are shifted into an array of so-called serial registers placed at the edge of the CCD array; the electrons of the second row are shifted to the first row and so on. At this point, the above-mentioned serial register shifts its content into a sensing output amplifier one pixel at a time, converting the electrons' charge to a voltage. Once all the pixels of the first row are read by the output amplifier, the shifting phase takes place again and the whole sensing process is repeated. This is so until all the pixels in the matrix are read out. This mechanism has an inherent electronic shutter in it, in that the exposure is over once all the matrix array has been shifted out and read. On the other hand, the exposure starts with an electronic reset of the CCD, during which all electrons in the array are swept away. Therefore, a mechanical shutter is not strictly necessary.

What makes all this useless, for common shutter speed used in photography, is its slowness. The shifting of a row, its reading one bit at a time, and repeating this process for all the thousands of rows present in a CCD is very time consuming. As an order of magnitude, the time required to read a row is about 130us. Reading 2500 lines, as for an 8 megapixel camera, would require 130us*2500 = 325ms. This is the time necessary in order to read the whole array and corresponds to 1/3 of a second. Not only this is a very slow time for photography, but it is not the maximum shutter speed achievable, neither. Indeed, while reading the first row through the charge detection output amplifier, all the other rows are still in the CCD's array and collecting incoming photons. Their exposure is therefore longer than the first row. The last row is read 325ms after the first one, so it is exposed to light 325ms more with respect to the first row. Besides, each row is in a different position within the matrix at each shifting phase, so smearing occurs. Hence, a practical shutter speed must be much slower than those 325ms. This mechanism is simply too slow to be used as a useful shutter.

Frame-transfer CCD

A faster solution is attained through frame-transfer CCDs. They break up the process of shifting and reading the array into two parts. The array is duplicated: one part (photosensitive or image array) acts exactly as the standard CCD array collecting incoming photons, while the second part acts just as a temporary storage area (storage array). The storage array is shielded from light, so that no electrons are generated by incoming photons. The timing is the following. At the end of the exposure, all the electrons in the image array are shifted (transferred) to the storage array. Only when all this shifting is over the reading phase begins. So, instead of shifting one row at a time and reading it pixel by pixel as in full-frame CCDs, in frame-transfer CCDs all the rows are shifted in a transient area altogether and only then they are read. The reading, that is the conversion of the number of electrons into a voltage, is done as it normally would in a standard full-frame CCD. It takes place in the storage array, however, and not in the photosensitive one. The rows of the storage array are so shifted one by one and read pixel by pixel. The advantage of this solution is that the transfer of the electrons from the photosensitive to the storage array is pretty fast and the longer reading phase is postponed. Once all the electrons are transferred into the storage array, the exposure is over, because it is optically shielded.

As an order of magnitude, a row can be shifted by one place in roughly 100ns, which is one thousand times faster than the full-frame architecture! This time is fast enough to provide a useful shutter for camcorder application, where small CCDs are utilized. For instance, a typical 754x484 CCD would require 100ns*484 = 48.4us which corresponds to 1/20000s. Again, this is not the faster attainable shutter speed for the same reasons of the previous paragraph. However, it is fast enough to offer a 1/1000 - 1/30 electronic shutter with sufficient acquisition rate.

The drawback of frame-transfer over full-frame CCDs is evident. As the array is duplicated, the area is doubled and this implies higher cost.

Interline CCD

What about an even faster shutter speed? Interline CCD still have a photosensitive and a masked storage array, but they are interlaced, so that each storage row is adjacent to its photosensitive counterpart. Photosensitive and storage rows are alternated. This means that just one shift is required in order to store the electrons safely from the photosensitive into the storage light-shielded array, instead of a number of shifts equal to the number of the rows. For instance, for an array with 2500 rows as in the previous example, the interline CCD offers a 2500 times faster shutter than a frame-transfer one! Any practical shutter speed is attainable with such a structure, independently on the number of rows in the sensor. The slow reading phase is then accomplished exploiting the storage array, just as in frame-transfer. Interline CCDs share the same drawback of the frame-transfer: they take a large area thus rising costs.

By Andrea Ghilardelli

More articles about photography at ilghila.com.

Brightness and RGB Histograms – No Clipping Allowed

Each time a photographer is going to shoot, he has to set the correct exposure for the photograph, i.e. aperture and shutter pair, and sometimes ISO setting, too. In particular, photographers crave for avoiding under- or over-exposure. There are many ways available to determine the correct exposure. This time we are going to see a rarely used method that has a great power and control in it and exploits the histograms all digital cameras and editing software offer nowadays.


Full article

Low Light Photography - One Long vs. Many Short

When shooting in subdued light, classic photography method is to select a very low shutter speed (tens of seconds or even more) to reveal the faintest objects. Therefore, we will take just one long exposure. One alternative way to proceed, however, is to take several short exposures of the same scene and then adding them up with editing software like Photoshop. This technique offers a wealth of advantages, leading up to better images and greater creativity.


Full article