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"FOCUS" Photography Contest Winners :
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1ST PLACE :
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all India photography : best 6
Partha Dam Photography
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Sibashis Manna Photography
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Shikhar Sharma photography
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High-dynamic-range imaging :
High-dynamic-range imaging (HDRI or HDR) is a set of techniques used in imaging and photography to reproduce a greater dynamic range of luminosity than possible using standard digital imaging or photographic techniques.
HDR images can represent a greater range of luminance levels found in real-world scenes, from direct sunlight to faint nebula. It is often achieved by capturing and then combining different exposures of the same subject matter. Non-HDR cameras take photographs with a limited exposure range, resulting in the loss of detail in bright or dark areas. HDR compensates for this loss of detail by capturing multiple photographs at different exposure levels and combining them to produce a photograph representative of a broader tonal range. The two primary types of HDR images are computer renderings and images resulting from merging multiple low-dynamic-range (LDR) or standard-dynamic-range (SDR) photographs. HDR images can also be acquired using special image sensors, like oversampled binary image sensor. Tone mapping methods, which reduce overall contrast to facilitate display of HDR images on devices with lower dynamic range, can be applied to produce images with preserved or exaggerated local contrast for artistic effect. In photography, dynamic range is measured in EV differences (known as stops) between the brightest and darkest parts of the image that show detail. An increase of one EV, or one stop, represents a doubling of the amount of light. High-dynamic-range photographs are generally achieved by capturing multiple standard photographs, often using exposure bracketing, and then merging them into an HDR image. Digital photographs are often encoded in a camera's raw image format, because 8 bit JPEG encoding doesn't offer enough values to allow fine transitions (and introduces undesirable effects due to the lossy compression). The images from any camera that allows manual exposure control can be used to create HDR images. This includes film cameras, though the images may need to be digitized so they can be processed with software HDR methods. Some cameras have an auto exposure bracketing (AEB) feature with a far greater dynamic range than others, from the 3 EV of the Canon EOS 40D, to the 18 EV of the Canon EOS-1D Mark II.As the popularity of this imaging method |
grows, several camera manufactures are now offering built-in HDR features. For example, the Pentax K-7 DSLR has an HDR mode that captures an HDR image and outputs (only) a tone mapped JPEG file.The Canon PowerShot G12, Canon PowerShot S95 and Canon PowerShot S100 offer similar features in a smaller format. Even some smartphones now include HDR modes, and most platforms have apps that provide HDR picture taking.
Color film negatives and slides consist of multiple film layers that respond to light differently. As a consequence, transparent originals (especially positive slides) feature a very high dynamic range. Comparison with traditional digital images : Information stored in high-dynamic-range images typically corresponds to the physical values of luminance or radiance that can be observed in the real world. This is different from traditional digital images, which represent colors that should appear on a monitor or a paper print. Therefore, HDR image formats are often called scene-referred, in contrast to traditional digital images, which are device-referred or output-referred. Furthermore, traditional images are usually encoded for the human visual system (maximizing the visual information stored in the fixed number of bits), which is usually called gamma encoding or gamma correction. The values stored for HDR images are often gamma compressed(power law) or logarithmically encoded, or floating-point linear values, since fixed-point linear encodings are increasingly inefficient over higher dynamic ranges. HDR images often don't use fixed ranges per color channel—other than for traditional images—to represent many more colors over a much wider dynamic range. For that purpose, they don't use integer values to represent the single color channels (e.g., 0-255 in an 8 bit per pixel interval for red, green and blue) but instead use a floating point representation. Common are 16-bit (half precision) or 32-bit floating point numbers to represent HDR pixels. However, when the appropriate transfer function is used, HDR pixels for some applications can be represented with as few as 10–12 bits for luminance and 8 bits for chrominance without introducing any visible quantization artifacts. |
Tone mapping :
Tone mapping is a technique used in image processing and computer graphics to map one set of colors to another in order to approximate the appearance of high dynamic range images in a medium that has a more limited dynamic range. Print-outs, CRT or LCD monitors, and projectors all have a limited dynamic range that is inadequate to reproduce the full range of light intensities present in natural scenes. Tone mapping addresses the problem of strong contrast reduction from the scene radiance to the displayable range while preserving the image details and color appearance important to appreciate the original scene content.
Tone mapping in digital photography :
Forms of tone mapping long precede digital photography. The manipulation of film and development process to render high contrast scenes, especially those shot in bright sunlight, on printing paper with a relatively low dynamic range, is effectively a form of tone mapping, although it is not usually called that. Local adjustment of tonality in film processing is primarily done via dodging and burning, and is particularly advocated by and associated with Ansel Adams, as described in his book The Print; see also his Zone System.
The normal process of exposure compensation, brightening shadows and altering contrast applied globally to digital images as part of a professional or serious amateur workflow is also a form of tone mapping.
However, HDR tone mapping, usually using local operators, has become increasingly popular amongst digital photographers as a post-processing technique, where several exposures at different shutter speeds are combined to produce an HDR image and a tone mapping operator is then applied to the result. There are now many examples of locally tone mapped digital images, inaccurately known as "HDR photographs", on the internet, and these are of varying quality. This popularity is partly driven by the distinctive appearance of locally tone mapped images, which many people find attractive, and partly by a desire to capture high-contrast scenes that are hard or impossible to photograph in a single exposure, and may not render attractively even when they can be captured. Although digital sensors actually capture a higher dynamic range than film, they completely lose detail in extreme highlights, clipping them to pure white, producing an unattractive result when compared with negative film, which tends to retain colour and some detail in highlights.
In some cases local tone mapping is used even though the dynamic range of the source image could be captured on the target media, either to produce the distinctive appearance of a locally tone mapped image, or to produce an image closer to the photographer's artistic vision of the scene by removing sharp contrasts, which often look unattractive. In some cases, tone mapped images are produced from a single exposure which is then manipulated with conventional processing tools to produce the inputs to the HDR image generation process. This avoids the artifacts that can appear when different exposures are combined, due to moving objects in the scene or camera shake. However, when tone mapping is applied to a single exposure in this way, the intermediate image has only normal dynamic range, and the amount of shadow or highlight detail that can be rendered is only that which was captured in the original exposure.
Tone mapping in digital photography :
Forms of tone mapping long precede digital photography. The manipulation of film and development process to render high contrast scenes, especially those shot in bright sunlight, on printing paper with a relatively low dynamic range, is effectively a form of tone mapping, although it is not usually called that. Local adjustment of tonality in film processing is primarily done via dodging and burning, and is particularly advocated by and associated with Ansel Adams, as described in his book The Print; see also his Zone System.
The normal process of exposure compensation, brightening shadows and altering contrast applied globally to digital images as part of a professional or serious amateur workflow is also a form of tone mapping.
However, HDR tone mapping, usually using local operators, has become increasingly popular amongst digital photographers as a post-processing technique, where several exposures at different shutter speeds are combined to produce an HDR image and a tone mapping operator is then applied to the result. There are now many examples of locally tone mapped digital images, inaccurately known as "HDR photographs", on the internet, and these are of varying quality. This popularity is partly driven by the distinctive appearance of locally tone mapped images, which many people find attractive, and partly by a desire to capture high-contrast scenes that are hard or impossible to photograph in a single exposure, and may not render attractively even when they can be captured. Although digital sensors actually capture a higher dynamic range than film, they completely lose detail in extreme highlights, clipping them to pure white, producing an unattractive result when compared with negative film, which tends to retain colour and some detail in highlights.
In some cases local tone mapping is used even though the dynamic range of the source image could be captured on the target media, either to produce the distinctive appearance of a locally tone mapped image, or to produce an image closer to the photographer's artistic vision of the scene by removing sharp contrasts, which often look unattractive. In some cases, tone mapped images are produced from a single exposure which is then manipulated with conventional processing tools to produce the inputs to the HDR image generation process. This avoids the artifacts that can appear when different exposures are combined, due to moving objects in the scene or camera shake. However, when tone mapping is applied to a single exposure in this way, the intermediate image has only normal dynamic range, and the amount of shadow or highlight detail that can be rendered is only that which was captured in the original exposure.
Example of the imaging process :
The images on the right show the interior of a church, a scene which has a variation in radiance much larger than that which can be displayed on a monitor or recorded by a conventional camera. The six individual exposures from the camera show the radiance of the scene in some range transformed to the range of brightnesses that can be displayed on a monitor. The range of radiances recorded in each photo is limited, so not all details can be displayed at once: for example, details of the dark church interior cannot be displayed at the same time as those of the bright stained-glass window. An algorithm is applied to the six images to recreate the high dynamic range radiance map of the original scene (a high dynamic range image). Alternatively, some higher-end consumer and specialist scientific digital cameras are able to record a high dynamic range image directly, for example with RAW images.
In the ideal case, a camera might measure luminance directly and store this in the HDR image; however, most high dynamic range images produced by cameras today are not calibrated or even proportional to luminance, due to practical reasons such as cost and time required to measure accurate luminance values — it is often sufficient for artists to use multiple exposures to gain an "HDR image" which grossly approximates the true luminance signal.
The high dynamic range image is passed to a tone mapping operator, in this case a local operator, which transforms the image into a low dynamic range image suitable for viewing on a monitor. Relative to the church interior, the stained-glass window is displayed at a much lower brightness than a linear mapping between scene radiance and pixel intensity would produce. However, this inaccuracy is perceptually less important than the image detail, which can now be shown in both the window and the church interior simultaneously.
The images on the right show the interior of a church, a scene which has a variation in radiance much larger than that which can be displayed on a monitor or recorded by a conventional camera. The six individual exposures from the camera show the radiance of the scene in some range transformed to the range of brightnesses that can be displayed on a monitor. The range of radiances recorded in each photo is limited, so not all details can be displayed at once: for example, details of the dark church interior cannot be displayed at the same time as those of the bright stained-glass window. An algorithm is applied to the six images to recreate the high dynamic range radiance map of the original scene (a high dynamic range image). Alternatively, some higher-end consumer and specialist scientific digital cameras are able to record a high dynamic range image directly, for example with RAW images.
In the ideal case, a camera might measure luminance directly and store this in the HDR image; however, most high dynamic range images produced by cameras today are not calibrated or even proportional to luminance, due to practical reasons such as cost and time required to measure accurate luminance values — it is often sufficient for artists to use multiple exposures to gain an "HDR image" which grossly approximates the true luminance signal.
The high dynamic range image is passed to a tone mapping operator, in this case a local operator, which transforms the image into a low dynamic range image suitable for viewing on a monitor. Relative to the church interior, the stained-glass window is displayed at a much lower brightness than a linear mapping between scene radiance and pixel intensity would produce. However, this inaccuracy is perceptually less important than the image detail, which can now be shown in both the window and the church interior simultaneously.
Visual effect :
Local tone mapping produces a number of characteristic effects in images. These include halos around dark objects, a "painting-like" or "cartoon-like" appearance due to a lack of large global contrasts, and highly saturated colours. Many people find the resulting images attractive and these effects to add an interesting new set of choices for post-processing in digital photography. Some people believe that the results stray too far from realism, or find them unattractive, but these are aesthetic judgements, and often concern the choices made by the photographer during the tone mapping process, rather than being a necessary consequence of using tone mapping.
Not all tone mapped images are visually distinctive. Reducing dynamic range with tone mapping is often useful in bright sunlit scenes, where the difference in intensity between direct illumination and shadow is great. In these cases the global contrast of the scene is reduced, but the local contrast maintained, while the image as a whole continues to look natural. Use of tone mapping in this context may not be apparent from the final image:
Local tone mapping produces a number of characteristic effects in images. These include halos around dark objects, a "painting-like" or "cartoon-like" appearance due to a lack of large global contrasts, and highly saturated colours. Many people find the resulting images attractive and these effects to add an interesting new set of choices for post-processing in digital photography. Some people believe that the results stray too far from realism, or find them unattractive, but these are aesthetic judgements, and often concern the choices made by the photographer during the tone mapping process, rather than being a necessary consequence of using tone mapping.
Not all tone mapped images are visually distinctive. Reducing dynamic range with tone mapping is often useful in bright sunlit scenes, where the difference in intensity between direct illumination and shadow is great. In these cases the global contrast of the scene is reduced, but the local contrast maintained, while the image as a whole continues to look natural. Use of tone mapping in this context may not be apparent from the final image:
Tone mapping can also produce distinctive visual effects in the final image, such as the visible halo around the tower in the Cornell Law School image below. It can be used to produce these effects even when the dynamic range of the original image is not particularly high. Halos in images come about because the local tone mapping operator will brighten areas around dark objects, in order to maintain the local contrast in the original image, which fools the human visual system into perceiving the dark objects as being dark, even if their actual luminance is the same as that of areas of the image perceived as being bright. Usually this effect is subtle, but if the contrasts in the original image are extreme, or the photographer deliberately sets the luminance gradient to be very steep, the halos become visible.
photography of the month :
Guest Photographer : Sibashis MannaIt has been 5 years m in photography, an IT guy by profession and freelance photographer by passion. Previously m in painting and then photography is most probably the transformation from that.
I like to shoot people, their rituals, their culture, roadside stories and lot more. During shoot I like the most is.... dilute with the environment, the subjects, that makes much easy to shoot any situation or the environment is.
Now I use nikon D5000 and D7000 bodies .... and lenses are... 10-20mm f4-5.6 sigma, 17-50mm f2.8 tamron, 50mm f1.8D nikon, 85mm f1.8D nikon and 70-300mm f4.5-5.6 VR nikon.
I'm very much thankful for publishing my work in whatzupkolkata-a very well organised website to focus the upcoming talents. i hope that, these initiatives will help a lot to budding talents. Well done Whatzup kolkata, Thank you.
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Partha dam photographyক্যামেরা- শব্দটির প্রতি আমার আকর্ষণ ঠিক কবে থেকে, তা আজ আর মনে নেই আমার। বলতে পারো, আমি নই, ক্যামেরাই আমাকে পছন্দ করেছে। যখন প্রথম ফটো তোলা শুরু করি, নিজস্ব কোনো ক্যামেরাই ছিল না আমার। বন্ধুর ক্যামেরা ধার করে ফটো তোলার হাতেখড়ি।
তারপর বহু কষ্টে, বহু পরিশ্রমে নিজের ক্যামেরা কেনা। সে কথা বরং আজ থাক। দীর্ঘ কাহিনি। শুধু এটুকু বলতে পারি, ছবি তোলা আমার কাছে কোনোদিনই একটা কাজ মাত্র নয়। আমার প্যাশন, আমার লাইফ-লাইন। আমার এই আবেগের দাম দেয় নি অনেকেই। হয়তো নেহাৎই খরচের খাতায় নাম লিখিয়েছি আমি। তবু ছবি তোলার পাগলামিটা ছাড়তে পারি নি। এর জন্য অবশ্য চাকরিকে ছাড়তে বিন্দু মাত্র দ্বিধা হয়নি আমার। অর্থ আমার জীবনের অর্থ হয়ে উঠতে পারেনি কোনোদিনই।গতে বাঁধা জীবন আমার জন্য নয়। তাই আজ আমার নেশা আর পেশা মিলেমিশে এক হয়ে গেছে।
ফটোগ্রাফির ব্যকরণ শেখার সুযোগ পাই নি। বরং ফটোগ্রাফিই আমায় শিখিয়েছে পৃথিবীকে নতুন চোখে দেখতে। কত বিচিত্র বিষয় ছড়িয়ে আছে আমাদেরই আশেপাশে। দরকার শুধু সঠিক অ্যাঙ্গলটা বোঝার ক্ষমতাটার। আর তারপরই যেন বাঙ্ময় হয়ে ওঠে একেকটি ছবি। তাই প্রকৃ্তিকেই ফ্রেম করে আমার পথ চলা শুরু হলেও এখন আমার আকর্ষণের কেন্দ্র হয়ে উঠেছে "wild life photography"। ভবিষ্যৎ পরিকল্পনা নিয়ে মাথা ঘামাতে রাজি নই আমি। পৃথিবীর বিচিত্র সৃষ্টিকে ফ্রেম বন্দি করতে চাই শুধু। আর চাই জীবনের শেষ দিন পর্যন্ত ছবি তুলতে, আর আমার তোলা ছবির মধ্যেই বেঁচে থাকতে।
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ayan mukherjee phototographyI started shooting from the year 2009. In May,2009 I got a simple point & shoot camera Sony CyberShot Dsc W300. As every other photographer, I started in my backward clicking flowers, insects etc . I use to upload them to social networking sites and they were appreciated well by my friends. Then I went to Digha in December,2009 with my family. That was my 1st outing with my camera. The pictures from that trip made me believe that I can take up photography as a serious hobby.
I have always got support from my family in the matter of photography. Especially my mom and sister has been a constant supporter of my passion.
I clicked with that point and shoot for near about 4 years. In those 4 years I came in contact with members of PHOTOGRAPHIC SOCIETY OF ASANSOL, Asansol. I had learnt a lot from the senior members of this photo club. I should mention the name of Mr.Malay Chatterjee ,who had given me the first ever formal teachings about photography basics and rules. Also, I need to say about Mr. Sandip Halder ,Mr.Sombit Mondal,Mr. Samir Sarkar who have been a constant support for me. I came to know about FIAP salons from them and started participating. Now, I am very near to prestigious AFIAP distinction. I have got many Acceptances and awards from various national and international salons. Passion about photography : I am highly passionate about photography. It’s like a drug to me which makes my life better to live. It started as a mere hobby, but now it has turned into my obsession.
Inspiration : My inspiration is National Geography. Whenever I feel tired, the yellow rectangle always inspired me. My dream is to get published in the covers of that prestigious magazine. Real incidents that you have faced during photography : Only thing which I want to mention in this question is that its always very tough to shoot in the streets. People will oppose you many times while taking their portraits and will ask you thousands of questions about you and your purpose of clicking these shots.So its always better to carry a photo id proof of any damn photo-club or institution. This helps a lot in clarifying their questions.Also try to go in a group of atleast 2-3 people which will again help to gain their trust. The gears you use : Nikon D7000, NIKKOR 18-105 VR F3.5-5.6, NIKKOR 50MM F 1.8,Sony Tripod
Expectation from Whatzup kolkata : WHATZUP KOLKATA is a great platform for all upcoming artists. They are a real help for us. Besides publicity and exposure, if they can arrange for some monetary gain/help to the artists by some means ,it will be a great effort. |