If you have a box of old analogue photos at home, you may be thinking about making digital copies of them. Being able to access your entire family photo collection using your computer is a fantastic thing.
However, unless you understand which type of resolution is the best to use when scanning photos, the digital images may turn out to be of poor quality. Below is a guide which will help you to get the best possible quality images when scanning images.
The term resolution refers to the level captured by a scanner. It is measured using dots-per-inch (dpi). The greater the number the dots per inch used, the greater the detail the final digital image with have. Many imaging software programs will allow you to select the dpi level you wish to use when scanning photographs.
The range of possible options will typically run between 50 dpi all the way to 8000 dpi plus. If you are a novice, it can be difficult to know which dpi setting is best for you.
The dpi is the critical number which will determine 3 important elements of the scan:
- The level of detail: The more dots of color per inch, will increase the fidelity of the image.
- The size of the digital image: This will dictate how many pixels are available. Pixels are the digital equivalent of dots-per-inch. The larger the image size, the greater the number of pixels and the more detail can be held. If you set your scanner to a very high dpi but save it as a very small digital image, most of the detail will be lost.
- The file size: The final size of the digital image file will depend upon the level of dpi selected during scanning and the image size. Greater detail and larger digital images will increase the final file size.
Deciding which Resolution to Choose
It is important that you decide which resolution you wish to use before you begin to scan your photos. If you do not do this, you run the risk of getting halfway through your photo collection before realizing that the images do not contain enough detail, which means you will have to start again.
A common mistake which people make when choosing the resolution is to choose the dpi based on the length of time it will take to complete each scan. The higher the dpi, the greater the length of time required for the scanner to capture the image and for the software to process this information.
At a low setting, such as 150 dpi, it will take around 10 seconds to scan and transmit an image. At a high setting, such as 4800 dpi, it will take 6 minutes to scan the same image. If you choose a low dpi so you can scan the images you could be setting yourself up for failure.
Scanning at a Low DPI
Although scanning at a low dpi setting will result in a reduced scanning time, it will also dramatically reduce the resolution of the digital image which is produced. This will cause the digital images to look grainy and unclear when viewed on a computer screen.
If you plan to reprint the images, you should bear in mind that standard printer paper was not designed to hold a great deal of detail. If you select a low dpi (below 500 dpi), the results when printed onto standard office paper will not be good.
If you want to achieve better results, you should consider printing the images onto professional photographic paper which is designed to hold much more detail. This will allow you to create a digital and a physical album which can be easily shared with friends and family.
Scanning at a High DPI
When you first purchase your scanner, the supporting paperwork may lead you to believe that you should scan at the higher dpi settings. If you have spent quite a lot of money purchasing your scanner, you may feel that by scanning at 8000 dpi you are getting your money’s worth.
While scanning at a very high dpi will not do any harm to your photographs, you should be aware that choosing the higher settings will not necessarily create a better result that a medium dpi setting. If you are scanning prints, you will not be able to achieve any more detail that the level already contained in the photographic print.
It is important to remember that higher dpi settings will increase the size of the digital file, which means you will need a large hard drive in order to store them. You will also require a computer with a faster processor in order to speed up the rate at which the imaging software can process information from the scanner.
For example, a scan of a print set at 4800 dpi would take up 2.22 GB of hard drive space. If you plan to transfer the digital images onto a DVD, you will only be able to fit two images of this size onto one disk.
Choosing the Best Resolution
Before you begin to scan your photographs, you should practice by scanning one test picture at different settings, such as 300, 600, and 1200 dpi. You should upload each digital image using your imaging software and then examine the outcome and compare the levels of detail.
When looking at the digital files, you should try to determine at which dpi setting you no longer see any more detail. You should the choose the dpi setting which is below this one.
The standard dpi setting for scanning photos typically between 600 and 800 dpi, as this provides the best level of detail and it only takes between 20 and 30 seconds to complete each scan.
Learning to scan photographs and finding the best resolution is often a process of trial and error. Once you have established the best setting, you can proceed with scanning the rest of your photo album.