Sometimes images are too big to scan in one piece especially the very long panorama photos that can reach well over 30 inches and bigger than 50 inches sometimes!
Scanning Problem: The scans don’t match?
When you scan a photo with multiple scans, you may find that the pieces end up looking different. The tones and exposure and even colour may look great on some and totally different on others, what is going on?
When your scanner when set to automatic just like a digital camera set to “auto”, it will exposure and correct the image where and how it sees fit. Images with more dark tones in them, may be compensated for and end up lighter and vice-verse for light images ending up darker. This is very important when scanning colour photos as it quite common for the colours to change too! Its important to get all your scans all the same for a perfect match.
What can you do? You can scan this type of image in pieces and then use PhotoShop to stitch them back together. I will use and example of a photo around 56 inches long of some windmills. It was scanned in five separate sections with an overlap or around 25% per photo and with all your scanners auto exposure setting turned off. This is to ensure that all the separate scans are exactly the same. If you leave your scanner to auto correct each one then they will all end up with slightly different tones and contrast which wont match well when photoshop comes to stitch them together. Once your image is scanned save the files off to a folder called panorama or something useful to you.
Below is the place to find the photo merge or stitch menu to start the photo stitching process once we have our scans saved properly. You can read more on saving the individual scans here saving your scanned photos correctly for photo restoration
Next, browse to where we saved the images.
Select the “Auto” option from the radio buttons and select “blend images together” from the check box below the list of files you browsed for just now. Then select OK.
In the finished result above after PhotoShop has finished stitching the layers, each one will be on a separate layer allowing you to fine tune them in case the stitch was not 100% accurate.
You can see here that I have switched off one of the layers so you can see how photoshop has blended the image. Its done in a nice, seemingly random fashion which is the best blend route and so that it cannot be seen when you zoom in and inspect it. Which is of course the way we want it, totally invisible!
There are not many occasions when it gets it wrong. I have had 2 or 3 instances when stitching school photos with many people together that two or more heads get replicated. Its very rare but can be corrected by manually painting over the masks on the layers. To do this you click on the black mask of the layer that wasn’t blended properly and paint with black or white soft brush, to add or remove the offending or misaligned part of the image.
TOP TIP: To scan images taller as well as wider than your scanner you can overlap the next row, both at the top and to the right..