Scanned slide image quality is determined by the combined quality of the 9 factors shown to the right. Follow the links for all the details about digital image quality.
The grain size of the film in a slide is about 1/5000 inch, so to capture the full resolution in your slides, it is important to have the scanning done at a resolution of at least 5,000 Dots Per Inch (DPI). Our slide scanning process produces a resolution of 6,000 DPI, which is the best in the industry. However, at such high resolutions, dynamic range starts to dominate. Knowing this, we created equipment which could record a dynamic range of a half million to one, compared to other scanning equipment which records a dynamic range of one tenth of this.
The popularity of digital cameras over the last 20 years drove the development of large, sensitive and affordable optical sensors. Combined with the inexpensive availability of massive computing power, this opened the door to the next generation of slide scanning technology, and that is what DpsDave uses to digitize your slides.
These photographs contain our history and are irreplaceable. In today’s dollars, each slide cost at least $2.00 each, and many of the cameras cost over a thousand dollars! You’ve already got a fair amount of money wrapped up in the images, so it makes sense to spend a little more and bring them into the digital age.
As mentioned, nine factors determine digitize slides services quality. The information presented here discusses the factors necessary for slide quality. Amazing results emerge with the use of new technology incorporated by Slide IQ.
Dynamic range is the ability of the scanning system to record a contrast. It describes the ratio between maximum measurable light intensities and the minimum. The naked eye does not see true white or black. Reflectivity of subjects and varying light source intensity makes a subject observable. The concept is a complicated one. Scanners, print displays, and subjects have their own range. Image transformation between devices affects the image produced.
Cropping changes a photo’s aspect ratio or recomposes the photo. A smaller image results from selecting a portion of the original and removal of the rest. It is possible to make a full frame image. The process removes unwanted elements and changes the photo balance. It produces the selected portion on the preferred page size.
Resolution is the detail captured by a scanner. It is measured in DPI, dots per inch. The dots are also called pixels. A scanned photo measuring 5 x 8 inches with a DPI of 300 is 1500 pixels wide and 2400 pixels high. The more pixels contained, the more detailed the image. Capturing every detail is ideal. Modern scanning equipment is capable of capturing more details than some photo or film contain. Detail for scanned images viewed on a computer or email is different from that of an 11 x 14 photo. It is a measure of image quality up to approximately 4000 DPI. It is still important beyond that point, but other image elements begin to make a difference. The best produced by anyone in the industry is 6000 DPI. Dynamic range begins to dominate at high resolutions of that caliber.
File types of digital images are either lossy or lossless. A lossless compression algorithm does not discard Information. Short abbreviations replace recurring file patterns. Reduction of the file size takes place. GIF, TIFF, PNG, and others are part of a collection of algorithms known as JPEG. The number of colors dictates the type of file used. More efficient image representation without an accuracy compromise occurs.
Saturation describes the image intensity. It determines whether an image looks dreary and drab or cheery and bright. Lumens are the units used in measuring the brightness. The minimum lumen rating for digital images is 1000. Editing increases saturation of under-exposed images, and decreases it on over-exposed images. The ability to increase is not the same as needing to increase. Real quality comes from understanding how to use digital imaging software to produce the intended effect.
Color that is detailed, refined and clear is crucial to pictures taken. Full-color image processing corrects the device’s developing characteristics. Management systems contain profiles, a matching module, and correct signals allowing original, displayed and printed matches. Software adjusts the signals described by the profiles. Maintaining the appearance requires gamut mapping to preserve chroma and tone.
Contrast differences distinguish objects from each other. Grayscale differentiation exists between a variety of image features. Intensity transformation corrects digital image deficiencies. An algorithm defines a set of rules for input and output pixel brightness values. Sufficient variance is necessary for the algorithm to perform adequately. Intensity transformation does not affect the position of the image.
Fade restoration and correction becomes necessary as dyes degrade. Over time, dyes fade and leave the film discolored. Faded photos lose black extremes and some whites. Individual hues fade at different rates. The levels tool of the software restores true black and white that formerly existed in a photo. Other adjustments correct balance and brightness.
Cleaning digital slides before scanning entails the use of special equipment. Scanner manufacturers recommend cleaning slides before scanning begins. Better image quality results. Scanner protection is in place. Every slide is subject to dust. Fingerprints leave droplets of oil. Using compressed air causes no damage to the surface and eliminates unwanted debris and dust.
IQ stands for installation qualification. It checks installation to ensure components mentioned here are correct and meet approved specifications. The purpose is original design compliance. IQ establishes that scanners receive image design and specifications. IQ Slide documents and checks the working environment to ensure suitable operation.
“You give us those nice bright colors,
You give us the greens of summers,
Makes you think all the world’s a sunny day!”
These are the images of the greatest generation, and these images deserve the best slide scanning there is. DpsDave is here to bring the best possible digitize slides service to you! Our motto is: Get More, Get it Fast, Spend Less. Try us out, and we think you will be pleased!