Bitonal or grayscale? That’s the question.
Choosing one over the other seems like a bit of a hassle, since you’re not really sure how your images will turn out once they’re converted from hard copy to digital. So how are you supposed to decide?
There’s no perfect answer, so in this article we’ll describe the capture methods available to you, provide some information and benefits of each type, and give some recommendations on how to choose one for your scanning project.
Digital Imaging Capture Methods
You have three choices of image capture methods when you decide to digitize your records: bitonal, grayscale, and color.
Bitonal, or black & white, scanning is the base method of creating digital images. When your hard copy records are scanned, the data is presented as pixels on a digital image. The pixels on the image are identified as either black or white.
Grayscale scanning provides for 256 shades of gray in each pixel, giving images much smoother transitions from white to black. Instead of each pixel being either black or white (as in bitonal scanning), each pixel can be one of 256 shades of gray. This generally provides for more realistic images.
Color scanning will give you the truest representation output of an original document, though it’s generally only used when the records actually have color on them! We won’t go into more detail here, as this is an article about bitonal and grayscale.
Scanning into bitonal images presents them in a way in which every pixel is either black or white.
Benefits of bitonal
- Small size
- Quick to retrieve (because of the small file size/data)
- If the original image is good (the original hard copy material), bitonal can easily have great image quality
Going with grayscale presents a scanned image where each pixel is a shade of gray (from a range of 256 shades) and provides a smoother transition from black to white than bitonal scanning.
Benefits of grayscale
- Truer representation of the original material
- Smoother transition from white to black because of the 256 shades of gray that can be applied in each pixel. You’re getting more tones with this option.
- Normally better for documents that aren’t in a great condition
- Allows for image manipulation after scanning (such as brightness and contrast adjustments in our Digital ReeL application)
Which One Should You Choose?
Not every scanning decision is black and white (pun very much intended!). Here are some things to consider when deciding on a bitonal or grayscale image delivery:
Choosing bitonal or grayscale images can depend on the end result you’re looking to achieve. Are these images just for statutory retention and you rarely, if ever, look at them? You might want bitonal.
Or are you accessing the records on a frequent basis and you want to have the best possible image since you’re seeing them constantly? Grayscale could be the better choice.
Quality is subjective, but in general grayscale images will provide the better quality result. So if you’re looking for optimal quality images, or want to scan for preservation reasons, you may want to lean towards receiving grayscale.
If the condition of the original material (such as microfilm or hard copy newsprint) is poor, grayscale is often the better choice to get a decent set of images. The tonality of the grayscale image allows smoother transitions and more options for software to choose a shade, rather than just black and white. If you go bitonal on a bad (original) image, you may get some poor results.
If size is an issue, bitonal is almost always the better option because it’s a smaller sized image compared to grayscale. Because the pixels are either black or white only, there is a lesser amount of data stored in the image file compared to the grayscale version.
Bitonal is usually the better choice for speed since the image sizes are smaller, allowing a quicker retrieval.
In most cases, there won’t be a difference for whichever option you choose. In fact, in our small projects we give you both bitonal and grayscale images anyway because it can be hard for you to decide what you want before you see it.
If you’re not interested in getting two sets of images, though (because maybe you have a large project with hundreds of thousands of images), you can assume that most scanning companies won’t charge you a difference for either option.
Ready to scan your records into bitonal or grayscale images? Call us at 800.359.3456 or email us at firstname.lastname@example.org, and we’ll help you convert your hard copies into digital.
Take a look at some of our other articles to learn more about digital conversion.
“Digitization & The Importance Of Historical Context” goes over how the historical context (the original record prior to digitization) can play an integral part in your conversion project. Choosing an image capture method is important, but make sure you don’t lose the context!
“Digital File Formats & Conversion Project Delivery” describes the ways in which you can receive your electronic records once they’re converted. This goes hand in hand with choosing an bitonal or grayscale.
“Digital Conversion: What Problem Are You Solving?” digs into why you’re running a conversion project. Before you jump in head first, make sure you have a good reason to proceed.