Technology, and especially the information technology field, can offer important services to philately. One of the most well-known such services, for example, is the possibility of a “virtual” presence in the auction “halls” through the relevant on-line capabilities provided by the auction houses; often, our only “weapon” as buyers are the scanned images of the lots we are interested in. The quality of such scans plays a big role not only in the presentation of an auction lot, but also in the general classification of a collection’s stamps with their correct color rendering.
Unfortunately, in the philatelic field, scanning is a purely mechanical task that is not given due importance—so, combined with other contributing factors, such as a mediocre screen, the end result of a scan ranges from disappointing to misleading in terms of stamps’ quality of color rendering when compared to its original printing outcome.
Scanner acquisition
As can be inferred from the above, it is important to know the correct way to scan our stamps, to achieve the best possible result in terms of faithful color rendering during scanning, as well as the best possible overall result.
First, we need to acquire a scanner with relatively good specifications. Devices costing just a few tens of euros/dollars will not bring the desired results because they are not designed for color accuracy or large resolutions. The features we should pay attention to when in the market for a scanning device are advanced color rendering and optical density capabilities (usually supplied by the manufacturer), 24-bit color depth support (for a range of 16.7 million colors; 48-bit color would be ideal) and a sufficiently large resolution—at least 1200dpi (dots per inch). Nowadays, there are several scanners with such capabilities at a price of less than 250 euros/dollars.
Placing stamps in the scanner
It is important to always scan our stamps under the same conditions: if we own more than one scanning device (even if it is the same model from the same manufacturer) we must always use the same one, since each has its own color rendering capabilities, which is a combination of many factors—from the initial factory settings to the environment and its frequency of use (and, consequently, its wear).
We must always keep the scanning surface clean: many times, in our attempt to place a stamp correctly, we may leave fingerprints that could affect scanning quality.
Also, we must always provide a stable background for the stamp on the scanner: it is not enough to place it “loose” or on an album sheet on the scanning device; we must have it placed in front of a background area, preferably black. It is recommended to use a truly black paper, and not to use the well-known black stock cards or album pages, which usually do not have a uniform surface and color.
Scanning stamps
Apart from the (usually simplistic) scanner software that manufacturers supply, which is sufficient for simple scanning and does not usually include post-image processing capabilities, no additional software is required for scanning. If we have some advanced color rendering and image processing needs, which we will examine below, then specialized image processing software is required.
During scanning, it is advisable not to choose the specialized image processing functions/options provided by some manufacturers through their scanning software (examples: unsharp masking, color restoration, dust removal, automatic exposure, auto contrast, auto color, white-balance correction and sharpening, etc.) since these are mainly aimed at an audience that scans photos that need some correction—on the contrary, in our case nothing should be altered from the original image of the stamp.
We must make sure that the resolution is as large as it needs to be, to bring out all the details of the design of a stamp—1200 dpi is recommended for good detail rendering and 2400 dpi is recommended, if supported. Two important points where we need to be careful:
a) The supported resolution must be optical (through the device) and not through software: many manufacturers advertise large resolutions, but these are achieved “artificially” through software (a method more commonly known as interpolation) and are not an intrinsic feature of the scanner as a hardware capability.
b) The higher the resolution of a scan, the larger the size of the image and the disk space that the final file will occupy, while it also takes longer to open and/or undergo some processing. For example, a 20 × 20 mm surface scan at 600 dpi gives an image of 472 × 472 pixels, while at 2400 dpi the resolution is quadrupled, to 1890 × 1890 pixels (amounting to sixteen times the pixel count, and potentially up to roughly sixteen times the uncompressed file size). Depending on the technical characteristics of a computer, a large image in very high resolution can create delays of several seconds (or minutes, in older devices) to be displayed or processed.
It is recommended that the image be saved in some type of file format that does not “lose information” due to compression such as PNG or lossless/uncompressed TIFF; if the popular JPEG format (.jpg file extension) is selected, choose the highest quality setting, but bear in mind that, even though some image editors may claim a “lossless” JPEG save by offering 0% compression, this is not actually true, as JPEG is lossy by design. However, the PNG/TIFF lossless option will result in a fairly large file size. If we have to scan hundreds of individual stamps in a collection this can create a space problem; it is thus recommended to use JPEG with as little compression as possible, so that the decrease in image quality due to compression is not apparent.
Color rendering
Even professional scanners cannot be assumed to accurately render the shade of the object being scanned without proper calibration and profiling. Although it is always possible to edit the image afterwards to try to achieve its true hue, there are two problems with this approach: a) the visual perception of a stamp’s actual hue is always subjective and can hardly be successfully corrected after processing, and b) who wants to edit each image after each scan to try to manipulate it to reach its original hue?
So, calibration and profiling are the technological tools we must use to achieve the above. Calibration sets the scanner to work based on a stable, known state. Profiling creates a file that is used by an image processing application in a way that we will see immediately afterwards.
Profiling requires a corresponding application (software), and a table of known color standards called an IT8 target. This target is scanned by the scanner, with the software comparing the difference (the delta) between the scanner’s color rendering and the “desired” values (the IT8 target’s known reference values), thus creating a profile (more commonly known as an ICC profile) which is essentially a file that describes how the scanner renders color and that the image editor “consults” in order to output a scan with shades as close as possible to the real ones. Important note: the image editing software must support ICC profiles, which is usually the case with most well-known (and usually more expensive) programs in the field. Bear in mind that for serious philatelic color measurement, even a calibrated and profiled scanner is not equivalent to measuring a stamp with a dedicated scientific device: a spectrophotometer. A future blog post will review a rather affordable spectrophotometer; so, stay tuned!
At the end of this short journey in the field of color, we must emphasize that the fact that this process provides a correctly colored image does not mean that we will see it correctly: this is because another factor comes into play here: the screen. The latter must also be of high image (color rendering) quality or, even better, be calibrated. We will not talk about this process, since it is outside the scope of this topic, but it is a parameter that we should consider so as not to be disappointed by a seemingly mediocre visual result.
Conclusion
We believe that with this article we have given the reader a first idea of the beautiful world of scanning and color and highlighted some details about this process that are not widely known to the philatelic (and non-philatelic) public. Scanning involves color, which is not just an art, but also a science and we should treat it that way if we want to achieve perfect results.
Sray tuned for more color-related blog posts in the near future.
This is an adaptation of an article written for the Greek philatelic press and published around the end of 2020/beginning of 2021. A commercial product mentioned in the original article has been removed, as it is now out of production. Additionally, some points have been further clarified. Enjoy scanning your Hellas stamps!