In addition to my previous post about Digital Post Porocessing, today I will write about Digital Technology in Photography - the process system that ocures inside the camera.
Digital Photography is a form of photography that uses digital technology to make images of subjects. It is one of several form of digital imaging as digital photography can be created also by non-photographic equipement (computer tomography scanners, radio telescopes or by scanning conventional (film) images). Digital sensors read the intensity of light as filtered through different color filters and convert an optical image into electrical signal. There are several main types of color image sensors, differing by the means of the color separation mechanism:
- Bayer sensor produces as many RGB pixels as photosensors through CFA interpolation or demosaicing
- Foveon X3 sensor produces uninterpolated image files with one-third as many RGB pixels as photosensors
- 3CCD produces image files using three discret image sensors with color separation done by a dichroic prism.
It is difficult to compare the resolutions based on the megapixel ratings of these types of sensors, and therefore sometimes subject of dispute. 3CCD considers the best quality and is the most expencive.
Digital memory devices store the digital image information, either as RGB color space or as raw data. The quality of a digital image is the sum of various factors, many of which are similar to film cameras. Pixel count (typically listed in megapixels, millions of pixels) is only one of the major factors, though it is the most heavily marketed.
The processing system inside the camera that turns the raw data into a color-balanced and pleasing photograph is the most critical, which is why some 4+ megapixel cameras perform better than higher-end cameras.
Therefore, image quality depends on:
- lens quality (resolution, distortion, dispertion)
- capture medium (sensor)
- capture format (pixel count, digital file type RAW/JPEG/TIFF)
- processing digital and or chemical processing of negativ and print
Images taken with digital cameras often lack on detail, depth and in dark areas often loose full details. It is best visible in image sizes from 800x600 pixels and above. To my disappointment, Canon images often lack on detail and good quality than those from Nikon, even thought Canon has put much attention to the noise reduction in its EOS series. The luck on detail remains from low up to high ISO and image looks more smeared or glazed. Nikon probably lacks on noise, but the image quality and details are much better. That noise is easy to be reduced by post-processing in Lightroom.
In my opinion Nikon D90 has the best image quality even thought it has lower ISO range than D300 or D700 or those from Canon EOS series. Surprisingly, Canon G11 has the best and the clearest image quality at ISO 100 and ISO 200. Even the background was very clear. My Sony DSC-W200 had also better images than most DSLR. D90 takes even better pictures in lower ISO than D3S or D3X. I was only disappointed by the low quality of an outdoor image. Here are other cameras better than D90. I still notice the lack on detail in the background or dark areas.
You can compare image quality with Imaging Resource Comparometer
Digital Post-Processing or Darkroom of digital photography is a workflow that prepares digital images for web and print. The workflow can be based on the type of photography (fashion, fine art, wedding or event) and techniques and tips of post-processing (mentioned at the end of this topic). Every beginner and advanced photographers need to know how best to post-process their images. A basic knowledge in Digital Technology and software applications is required. In order to make this topic a short and clearly arranged read, I'll write more specific about Digital Technology in a separate post.
For me, the post-processing begins already in camera. Today, if you want to work in a professional way, you have to work with high end digital cameras that support RAW, JPEG and TIFF files. RAW and TIFF are large file formats that require more space on your memory card. They can be compressed or uncompressed, but the compression scheme is lossless. That means that, even if you manipulate the files and make them a little smaller, nothing will change on the image quality. On the other hand, JPEG files are much smaller and require smaller space on your memory card, the quality loss by post-processing is very high. Each time when you would open a JPEG file you will loose on image quality. The resolution of JEPG files are 72 pixels but a very good quality print requires minimum resolution of 150 pixels. The best print resolutions are between 200 and 300 pixels. For Photoshop users - keep in mind that each time you would change the image resolution, the image size will became larger, and you'll have to go back to its original format right after changing the resolution. Otherwise, the image will remain blury. To check the image quality, go to image preview and than click on actual pixels. It will show you the current image quality. Lightroom will automatically do this changes for you and save a high quality JPEG file with a resolution of 240 pixels.
TIFF files are the largest files and to save them on your memory card takes an amount of time. Most of the professional photographers are working with RAW files which can be converted in JPEG and TIFF files directly on camera or on PC. In order to save space on your memory card, I would recommend to convert your files on your PC. For the workflow you will need a good software application. I mostly work with Photoshop and Lightroom. GIMP is free software application and a good alternative for Adobe software.
RAW and TIFF files are ideal for the post-processing and you get better results as with JPEG. Most common and popular post-processing techniques are:
- basic adjastments
- quick and flexible photo color manipulations
- black and white Photoshop conversion techniques
- image retouching
- exposure blending
- sharpening technique
- noise reduction
- lense correction
- contrast, autolevels and batch processing
- photo enhancing using Dragan and David Hill effects
Here you can find good post-processing tutorials for all the above mentioned techniques.
I just came accross this article, or better said tutorial, which was twitted by Graphics_Info. This HDR tutorial is interesting for every beginner. It explains not only how to use Tone Mapping in Photoshop, it gives you instructions on how to take your own HDR photos. You will also find instructions on the post-processing not only in CS3+ but also CS2 and lower. If you don't have your own HDR photos to practice the Tone Mapping, you can use those enclosed by the tutorial writer.
Photomatix is also a good and easy to use post-processing software of HDR images. I would recommend Photomatix rather than comparable Photoshop plug-ins. It does a better job with midtones, shadows and saturation and produces images with a distinctive ethereal appearance.
Why is such a post-processing step necessary? If you have ever photographed a high contrast scene (for example panoramic scene), you know that even the best exposure will typically have blown out highlights and flat shadows. Photomatix offers two ways to solve this problem:
- HDR Tone Mapping: Reveal highlight and shadow details in an HDR image created from multiple exposures.
- Exposure Fusion: Merge differently exposed photographs into one image with increased dynamic range.
Here is a good Photomatix HDR tutorial written by Wayne Miller Photography. It explains exactly the same steps written in the above mentioned tutorial. Final results are done in Photomatix inspite in Photoshop.