Useful Definitions
Frame
One still image. A frame can be by itself or included with others on the same filmstrip. All our scanning is priced per frame, not per filmstrip.
Film Types
There are two types of photographic film – transparency and negative. All slides are transparencies. The image you see on the film is the same as it would appear in print or on a screen. With negatives, it is difficult to determine the color and quality of the image by looking at the film. We have scanned color negatives that are 70 years old and B&W negatives that are over 100 years old. Thus far, we have been able to get very good quality images from negatives. Most strips of standard photographic film are negatives. Panoramic, medium and large format film can be negatives or positives. Generally speaking, scans of negatives produce higher quality images than scans of the photos printed from negatives.
Negatives
One 35mm filmstrip contains four to six frames, each 35mm x 24mm. The frame number is printed on the top and/or bottom below the frame. 135 film is exactly 35mm wide. Medium format film may consist of a strip of 2-3 frames or only one frame. Large format film (4”x 5” or 8”x 10”) has only one image.
Slide Types
All standard slides are mounted in a 2” x 2” paper or plastic holder. For 35mm slides, the frame size (viewable image) is usually about 34mm x 23mm, although it does vary by manufacturer and slide age. Two other common slide types have a square viewable area. A 127 “super slide” has a frame size about 40mm x 40mm, and 28mm slides have a viewable area of about 26mm x 26mm. We charge the same price to scan any size slide in a standard 2” x 2” mount.
Medium & Large Format
120 (220 and 620) is a medium format film that is larger than the standard 35 mm negative or slide. Medium format film contains a range of frame sizes: 6.0 x 4.5cm, 6 x 6cm, 6 x 7cm, 6 x 8cm, 6 x 9cm, and 6 x 12cm, the most common being the 6 x 6cm size. The frame number is printed at the top or bottom of the film. Large format film comes in individual sheets (4” x 5” and 8” x 10”).
Digital Images – TIFF and JPEG Format
TIFF and JPEG are two different file formats for digital images. Both formats are recognized as international standards for digital images. Professional printers can make prints from images stored in JPEG or TIFF format.
TIFF (Tagged Image File Format) includes all the information from the original scanned image. It is a flexible format that is supported by all digital photo editing and publishing applications and contains all the information that a professional printing service may require. The size of the file is much larger than a JPEG (Joint Photographic Experts Group) formatted file. Images in TIFF format are labeled image_001.tif. For archiving purposes, the TIF format is ideal. TIF is the only standard digital imaging format with the capability for 16 bit color bit depth. Only the TIF format allows B&W film scanned in grayscale mode, Converted to JPG format, all digital images are in RGB color mode. Hi-DEF always provides each customer a set of digital images in TIF format. A TIF image is a “master file” that can be compressed to create a JPEG formatted image file at 8 bit RGB color.
Even if the original photo or film is B&W, all JPEG image files are 8 bit RGB color mode. JPEG compresses the image and some information is lost as a result. The file size is much smaller than a TIF image. A JPEG formatted image may be optimized for printing or for slide shows (PC or TV viewing). JPEG format is commonly used to display photographs in web photo galleries and slide shows. All JPEG formatted images are labeled image001.jpg. To avoid confusion, your print-ready images in this format will be on a disc labeled JPG.
Color Bit Depth (24 or 48)
All digital images displayed on video, TV screens or computer monitors are based on the RGB color mode, which is a mix of Red, Green, and Blue light in various proportions and intensities. Since all colors are a mix of three, 8 bits per color channel produces an image with 24 bit color depth. When viewing images on TV or computer screens, there is no perceivable difference between 24 and 48 bit color depth. Most desktop printers in use today can only print at 24 bit color.
The number of bits of color captured per pixel is related to the number of possible colors. The higher the number of bits per pixel, the greater the color depth of an image and the more vivid the color will appear on a print of the image. Since digital imaging is reductive, post-scan editing results in the loss of color bits. Note that TIF files in 48 bit color are twice the size of the same image in 24 color bit depth.
Grayscale has only one color (shades of gray between white to black) with the choice of 8 bit and 16 bit. For most B&W negatives, we scan in grayscale at 16 bit. In grayscale mode, scratches and any dust spots can only be removed in post-scan retouching.
Optical Resolution
A measure of how well a scanner can capture an image. It is the actual number of pixels that the scanner provides when scanning an image. The higher the optical resolution, the higher the quality of the image captured. Higher optical resolution will result in a better quality on-screen and printed image. Optical resolution is measured in pixels per inch (ppi). Increasing the scan resolution will result in greater detail, more pixels, a larger file size and simply a better quality print. If you have a large file, you can easily resize it to create a smaller version of the image without losing quality. However, the opposite is not true; you cannot make a digital image larger without losing quality (fewer pixels per inch). While an enlarged photo (from film) will appear blurred (not as sharp as the original), a poorer quality digital image appears “pixelated,” with broken up or noisy color images. For these reasons, all our scans are high resolution (more pixels than necessary for a standard size photo printed at 300 dpi (dots per inch).
Cropping
A digital image is made up of pixels. Cropping is the process of removing selected pixels from a digital image. An uncropped scan of a 35mm slide will contain a black border (slide mount) around the image, as do color negatives in the same strip of film. This border can be removed by cropping. The edges of slide mounts and non-image areas of all negatives are cropped before the final scan. As a result, the scanner interprets the “true” tonal range of colors contained in the film. With slides, the cropped digital image (in mm) will vary with the size of the mount.