How do they do it ? – Scanning Maps

Process used to scan a Historic Map and make available in a browsable format online.

The map used in this example is a large ~ 78 x 82cm (30.5″ x 32″) map of Dublin City and Environs from Thom’s Directory of 1906.

Scanner – A3 2400S A3 Scanner / Twain V 3.05 Driver

Software : IrfanView 4.44 , Paintshop Pro 5.00 , Affinity Photo 1.92

Zoomify Image Converter 2.3.2 & Javascript Viewer

The process for scanning the original map and joining the resulting images has recently become a little simpler to carry out a) due to the advances in image processing software, and b) due to my ‘new’ A3 scanner, which means that I now end up with about half the number of images to join together.

When I started scanning maps (c 2009 ?) with an A4 scanner the image scans were all manually straightened and joined –  a very time consuming process…

An A3 scanner covers twice the area so resulting in larger images and about half the number of scans so a smaller number of joins. Technology for joining images to make panorama now feature in many platforms, even iPhones, and modern photo processing software often contains sophisticated stacking and panorama functions, and also allow other adjustments and repairs to images.

This map is in good condition, only one small tear, and due to it’s storage location inside the cover shows no obvious sign of light damage, however the print quality is a little variable –  there are signs that the plate may have been as worn or clogged during this print.

Test scans showed that scanning at 300dpi colour was sufficient for the print resolution and quality of this map, and a series of scans down the left (Red 1 to 4) and right edges (Green 5 to 8) would cover most of the map with the cover down (to ensure focus and reduce fold marks) without undue folding etc, two addition scans of the centre portion (Blue 9 & 10) could then fill in any gaps.

Map areas for scanning

Basic adjustments were carried out on the images, e.g. ensuring key frames were lined up correctly to horizontal & vertical using map grid lines.

Scanned Map Images

Affinity photo was then used to merge each section – i.e. ‘left’ images 1 to 4, ‘right’ images 5 to 8, and centre images 9 and 10.

Three panoramas – left, centre and right

After basic cropping the three panoramas were then joined in one  master panorama after which some repairs and adjustments were carried out.

Next step is the Zoomify converter which takes the processed file and splits into a series of image tiles suitable for display by the custom JavaScript code.

Zoomify Converter creating the image tiles

Sample Image Tiles

All that remained was creating the associated HTMP/PHP file with a link to the tiles folder and adding the various menu links to show the new page and then zipping and uploading the new and updated files to the webserver.

Header of new Html/Php code

Complete…. Dublin City & environs – Thom’s 1906 Map

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