Chapter 7- Aspects of Digital Lighting Flashcards
Digitising of Analogue Photographic Images: Flatbed Scanner: How are these attached to a computer?
By USB port, although some older models will use SCSI or parallel port methods
Digitising of Analogue Photographic Images: Flatbed Scanner: What sort of light source and sensor does this sort of scanner have?
Built-in light source (flourescent or halogen) and a trilinear CCD sensor (RGB) fixed to a screw thread tracking rod that travels beneath the original image
Digitising of Analogue Photographic Images: Flatbed Scanner:What is one of the key aspects of the process to keep the same between the image and the digital file?
To minimise contrast gain
Digitising of Analogue Photographic Images: Flatbed Scanner: What bit depth would be required to create a photo-realistic image?
24-bit depth for an RGB colour image
32-bit depth for a CYMK image
Digitising of Analogue Photographic Images: Film Scanner: Why is this more suitable for film rather than the flatbed scanner?
Because the film material is much smaller so the scanner CCD sensor needs to have an increased number of photo-sites per area compared to a standard flatbed scanner sensor
Digitising of Analogue Photographic Images: Film Scanner: A good quality scanner should be able to reproduce what sized hard copy images without pixelation?
11 x 17 inch (with exception to higher end professional camera models)
Digitising of Analogue Photographic Images: Film Scanner: These also use a trilinear CCD sensor and use either their own or photoshop software to import the image (as does the flatbed scanner). How does this process differ?
Flatbed scanners work by detecting the levels of light being reflected off the surface of the photographic print but film scanners detect the level of light transmitted through the individual photographic film strips
Digitising of Analogue Photographic Images: Film Scanner: What bit depths do these film scanners have and why is this important?
Either 36, 42 or 48-bit depths which is important as the instruments need to detect subtle colour differences and capture the the original films full brightness range
Digitising of Analogue Photographic Images: Film Scanner: What do drum scanners achieve well?
Having high dynanic range (4.0) which increases image detail in dark areas
This is ddone by using Photomultiplier tube as opposed to trilinear CCD
Typically, lower dynamic range (2.4) is fine for reflective prints Medium ones (3.0) are sufficient for negative films High ones (3.6) are good for positive film
Image Film Formats: What will the images be composed of?
Pixels of vector data
Image Film Formats: What are file formats comprised of?
The file header and the image data
Image Film Formats: Film Scanner: What would a file header contain information on?
Horizontal and vertical dimension of the image (in pixels)
Image data type (colour, greyscale)
Image bit-depth
Compression technique
Image Film Formats: What would the image data comprise of?
Camera model type
Settings used e.g aperture, ISO, shutter speed
Image Film Formats: Raw Data Files: What is this?
A data file containing unchanged raw pixel information from the CCD or CMOS sensor. It contains just one red, blue or green value at each pixel location and no compression has occured so no artefacts will appear within the image
Image Film Formats: Raw Data Files: In a JPEG file, each colour is stored in an 8-bit value, providing 256 steps between lightest and darkest colours.With Raw, most cameras record in what bit per colour?
12-bit or 14-bit
Image Film Formats: Raw Data Files: What are the key advantages that a photographer has with a Raw file?
Better flexibility to correct over or under exposure
Better detail in murky shadows or bright image highlights
Adjustable white balance capabilities during post-production of images
Good for optical corrections and noise removal
You can revisit Raw data files and reprocess them as tech improves
Metadata (camera type, lens and focal length etc.) is recorded
Image Film Formats: Raw Data Files: What is the only standardised Raw format in Adobe?
Adobe Digital Negative format- this is what will be the standard in the future so can still read the files (unlike some others which may not still be around)
Image Film Formats: Raw Data Files: Which cameras produce Raw data files?
All digital medium format and all digital SLRs and a variety of high end compact cameras do as well as hybrid cameras
Remember that Raw file is just a term for a range of data files- it is not just a single thing
Image Film Formats: JPEG- Joint Photographic Experts Group: What level of compression can JPEG achieve with little perceptible loss of image?
10.1
Image Film Formats: JPEG- Joint Photographic Experts Group: What is the format based on?
Discrete cosine transform algorithm (DCT)
Image Film Formats: JPEG- Joint Photographic Experts Group: What does it sacrifice for good contrast and saturation?
Image detail
Image Film Formats: JPEG- Joint Photographic Experts Group: What has the JPEG committee released and how is it different from the DCT method?
JPEG 2000 uses wavelet-based compression methods which has many advantages over DCT
Image Film Formats: TIFF- Tagged Image File Format: What is this used for?
Images destined for commercial publishing i.e. magazines, journals and books where quality needed is very high
Image Film Formats: TIFF- Tagged Image File Format: Does this deal with compressed or uncompressed images?
Both in addition to storing bit-depth and resolution
Image Film Formats: TIFF- Tagged Image File Format: What was this originally made for and what system does it use to compress images?
Allow for cross-platform usage (movement of files between diffferent computer architectures)
Lempel-Ziv-Welch (LZW) compression is used- no image quality loss and so is referred to as lossless compression method
Image Film Formats: GIF- Graphics Interchange Format: Who developed this?
Internet service providers compuserve