ePerforationGauge         ... an electronic stamp perforation gauge Version 1.0 (22-Jan-2004) © 2004 P.P. Hek

home: www.eperforationgauge.com | mail: psquareh@eperforationgauge.com

Contents

Introduction
System Requirements
Usage
Download
Examples
News
FAQ's

Introduction

ePerforationGauge is a very useful tool to determine the perforation of a stamp that is displayed on a graphical image on a black(ish) background. Move the perforation gauge over the stamp to find the exact perforation or use the possibility of the program to automatically measure the perforation of one side or the perforations of two sides. Remarkable of ePerforationGauge is that (small) perforation problems will be corrected (e.g. a missing tooth). The most important condition for measuring the exact perforation is that the resolution in DPI (and scale in %) should be known of the stamp that is displayed on the graphical image. When the resolution and/or scale is not known but the stamp is a known variety, then the program can very probably still determine which variety it is. ePerforationGauge has all the varieties of the normal postage stamps of The Netherlands included; other varieties can be added manually. The automatic analysis takes place in (less than) a few seconds (depending on the size of the image and the speed of the computer) after which the approximated perforation to the nearest ¼ (0.25) is shown.

ePerforationGauge is developed and tested on the Windows® NT operating system. It has also been tested on the Windows 98 operating system. This also indicates that it also should work on other Windows 32-bits operating systems. There do exist some remarkable differences between the several Windows operating systems. The minimum memory requirement is not known. The necessary disk space is approximately 2 MB.

Usage

Resolution and scale

It is necessary to know the resolution in DPI (dots per inch) and scale in % of the stamp that is displayed on a graphical image in order to determine the correct perforation. The resolution and scale can be changed using the two combo boxes in the left upper corner.

The last selected resolution and scale is stored and used as default value when ePerforationGauge is started a next time. Is a specific resolution or scale not available in the list, then manually a resolution or scale can be specified. Place the cursor in the combo box, type the resolution or scale and finish with the Return (Enter) key. The possible values for the resolution range from 75 to 1200 (dpi); the possible values for the scale range from 50 to 500 (%). The symbols 'dpi' and '%' do not need to be specified: these are appended automatically when not specified.

Not every combination of resolution and scale seems (is) useful. The combination of resolution 75 dpi and scale 50 % results in a too small area to measure perforations. For the combination of resolution 1200 dpi and scale 500 %, 7 x 7 = 49 screens (of 1024 x 768 pixels) are necessary in order to see something useful.

Place the perforation gauge always on top

By default, the perforation gauge is always on top. This means that when another application is activated, the perforation gauge remains visible on the foreground. This can be disabled by the check box in the left upper corner.

Is the check box unchecked and another application is activated then the perforation gauge will move to the background (at least behind the activated application).

Moving and marking the perforation gauge

Use one of the four symbols to move the perforation gauge. Place the cursor on one of these symbols, click the left mouse button and keep the button down, drag the perforation gauge to the correct position and release the mouse button. In the above example the horizontal perforation of the stamp appears to be 12½ and te vertical perforation appears to be 12.

Is a perforation found, then this can be marked (as a reminder). Therefore click on a perforation indicator at the edge of the perforation gauge. By doing this, the colors of the perforation indicator are reversed: 12½ white on black becomes 12½ black on white.

Automatic determination of the perforation

For automatic determination of the horizontal perforation, the horizontal oriented black-red striped box is used; for the vertical perforation, the vertical oriented black-red striped box is used. The example above shows how to place this black-red striped box.

Place the perforation gauge on the correct position and after this, click on one of the following symbols:

for the determination of the horizontal perforation at the top side
for the determination of the horizontal perforation at the bottom side
for the determination of the vertical perforation at the left side
for the determination of the vertical perforation at the right side
for the determination of both the horizontal perforation at the top side and the vertical perforation at the left side
for the determination of both the horizontal perforation at the top side and the vertical perforation at the right side
for the determination of both the horizontal perforation at the bottom side and the vertical perforation at the left side
for the determination of both the horizontal perforation at the bottom side and the vertical perforation at the right side

In (less than) a few seconds the perforation is computed and shown on the screen.

The found perforation is marked at the edge of the perforation gauge (as can be done manually). The found teeth are indicated by a little white line, the holes are indicated by a little black line. This way it can be visually checked whether the determined perforation is plausible. Always use a few ways to measure the perforation(s) and compare at least the results of these different measurements.

Note: the horizontal perforation is marked at the left side of the perforation gauge and the vertical perforation is marked at the upper side of the perforation gauge!

Is it that simple? Yes and no. There are a few restrictions to the image being analysed.

• The image should not be too small, otherwise the perforation can not be determined reliable.
• The background color on which the stamp is displayed should be reasonably black, otherwise the stamp itself can not be identified; the analysis of a stamp on a white or light grey background will fail.
• The edges of the stamp should be reasonably white, otherwise the stamp itself can not be idenitfied; the analysis of a stamp with a strongly shifted stamp picture having dark colors will fail.
• The stamp should not be too heavily canceled, otherwise the perforation can not be determined reliably; although perforations from other edges where there is no or light cancellation can be reliable.
• The stamp picture itself should be positioned reasonably straight on the image, otherwise the algorithm to determine the perforation will fail.
• The perforation of the stamp should not be too heavily disturbed like missing teeth or very short teeth; minor perforation problems will be corrected; although perforations from other edges where there are minor or no perforation problems can be reliable.
• The stamp should not be imperforated or syncopated; although, many times, it will determine a perforation, but a visual inspection will proof otherwise.
• When the resolution and/or scale is not correct, the determined perforation will be wrong by definition; although the ratio between the horizontal and vertical perforation can provide enough information, in case this ratio is unique for a specific stamp.

There are also a few, more technical, restrictions:

• It is not possible to move the upper side of the perforation gauge outside the screen. The Windows operating system will then force the upper side of the perforation gauge to be inside the screen. It is possible to move the perforation gauge (far) outside the screen at the left-, right- and lower side of the screen.
• Some Windows operating sytsems (e.g. Windows NT) remain all parts of the perforation gauge visible while moving the perforation gauge and some Windows operating systems (e.g. Windows 98) only show the outside frame of the perforation gauge. The precise positioning of the perforation gauge can then be a little problematic.
• Due to the combinations of both restrictions metioned above it can be sometimes impossible to reach a certain part of the screen where a stamp is displayed.
• When the resolution and/or scale is changed many times, it can happen that the program 'crashes'. The graphical processing of the Windows operating sytems looks to be 'confused'. The cause of this has not been found (yet).

• When the perforation is measured on two slightly different areas, it will undoubtly sometimes happen that a different perforation is determined. This is primarily caused by the fact that slightly different positions are found for the teeth and that the distance between the teeth vary. This is again the result of the algorithm which analyses the image on basis of pixels (pixel = smallest visible dot on the screen) and the roundings (12.624 becomes 12½, 12.626 becomes 12¾). In general the following applies: the bigger the resolution of the image is, the more precise the result is of the computation (more pixels are being analysed).

When the algorithm that determines the perforation fails, then the perforation is given as a ?. The reason for failure is many times difficult to track down, but often it will be case that it fails because of one of the above restrictions. A simple example of this is the following: place a black-red striped box in a white area and determine automatically the perforation; the perforation will be guaranteed a ?.

Definition and look-up of known varieties

During startup of ePerforationGauge it is possible to define known varieties. These varieties should be listed in a normal text file, that can be maintained by any preferred text editor without layout facilities (e.g. Notepad, Wordpad, but not Word). At the installation, a ePerforationGauge.Txt file is included that contains all the varieties of the normal postage stamps of The Netherlands. Other varieties can be appended using a text editor. Lines in this file should apply to a specific format and this is:

• A line should always start with the stamp number and variety code (e.g. 22L); the variety code must be a non-numeric code
• After this, one (or more) spaces or tabs follow separating the perforation
• After this, the perforation is specified in the following formats:
• H : V
• H x V
• T
H is the horizontal perforation, V is the vertical perforation en T is the horizontal and vertical perforation in the case that these are equal. For the perforation, the '.'-sign and the ','-sign can be used as the decimal separator. The separator sign between the horizontal and vertical perforation shoud be either a ':'-character or a 'x'-character.

Examples of lines in this file could be:

22G 13.50:13.25
22H 12.50:12.00
22J 11.50:12.00
22K 12.50
22L 12.50

Empty lines or lines that start with a '#'-character are skipped completely. At startup, ePerforationGauge will re-format the ePerforationGauge.Txt file, this means for example that unnecessary spaces are removed. There are no informational messages about any errors in this file. To lines that are in error a '#'-character is inserted at the start of the line. Always backup this file before making changes and keep the backup in a safe place in order to be able to restore this file in the case that ePerforationGauge has to be installed again!

Examples of lines that are invalid:

22G13.50:13.25
22H 1a.50:12.00
22J 11.50-12.00

The first line has no space as separator between number and perforation, the second line has an incorrect horizontal perforation (1a.50) and the third line has an invalid separator sign (-) between the horizontal and vertical perforation.

Has the horizontal and vertical perforation been determined then the stamp can be selected from the combo box. For the given example, stamp nummer 22 should be selected. After this, the overview of all varieties for this number is displayed and for each variety it is indicated whether this variety is correct:

Whether a variety is correct is indicated by the following symbols:

• a green checkmark indicates that the perforation exactly matches with the known variety
• a yellow questionmark indicates that the horizontal and vertical perforation differs less than ¼^th of the known variety
• a red cross indicates that the horizontal or vertical perforation differs more than ¼^th of the known variety

After this, click on the -mark to continue with ePerforationGauge.

Unknown resolution and/or scale

When the resolution and/or scale is unknown for the stamp on the graphical image but the stamp is in the list of known varieties then the program can probably determine the correct variety. This is done on basis of the ratio between the perforations. Therefore try to select a scale that is reasonable to determine the perforation (note the problem that sometimes occurs when changing the resolution and/or scale many times). After this, select the stamp from the combo box and then it be will shown which variety it could be using the -symbol in a different column:

The given example is given for the perforation 10¼ * 9¾. The criterium that is used to decide that a variety could be correct is when the difference between the horizontal and vertical perforation is less than 0.025. (The ratio between 10¼ and 9¾ is 1.05128, the ratio between 12½ and 12 is 1.04167, the difference is 0.00961 and thus smaller than 0.025.)

In the case of an unknown resolution and/or scale it gets even easier and faster when the select function is used. The select function is started using the symbol. This causes the perforation gauge to disappear and the mouse pointer changes to a cross. The function is aborted by pressing the Esc key. Start the selection of the stamp by a click on the left mouse button (and keep the button down), move the mouse to the end of the selection and release the mouse button. After this, the perforation gauge appears again, an appropriate scale is selected, the perforation gauge is repositioned to the selected area and the determination of the horizontal and vertical perforation is started. Note that the selected area can not be too small since the scale would become less than 50%. Which horizontal (top or bottom) and vertical (left or right) is analysed depends on the start and the end of the selected area.

The reliability of ePerforationGauge becomes very questionable in this situation. Although the difference between 11 x 12 and 12 x 11 is rather clear in such a case.

Help

Click on the symbol or use the F1 key to show this page in the default Internet browser (e.g. Internet Explorer).

Ending the perforation gauge

Click on the symbol to exit from ePerforationGauge.

Final note on the usage

Although, as can be seen from the example, the ePerforationGauge tool can give very nice results, a physical examination of a stamp for the perforation is always the most reliable, so therefore use it only as an indication and never decide only on basis of this tool whether the given perforation is correct!

Download

Versions and Support

This is version 1 of ePerforationGauge and there are no intentions for future versions or even bug fixes. There are also no intentions to migrate the tool to other platforms. Unfortunately, due to an enormous lack of time, there is no support possible (or only very limited) on installation, usage, problems, etc. Please be aware that it can take some days before I can respond to e-mails.

I have been a stamp collector all my life and an ICT professional for many years now. This combination resulted in the development of this tool which I use regularly to inspect perforations. I have no idea if anyone is interested in this tool, but if there is enough interest, I will consider a more serious approach including bug fixes, improvements, versions, etc.

The first time, the full version should be installed, otherwise the latest version can be installed.

Full Version

Follow the next four steps to install the full version:

Step 1. Download the epg.zip file.
To download the full version click here with the left mouse button, select the option Save this program to disk and select any folder (e.g. C:\Tmp or C:\Temp) in the Save As dialogue that follows to store the epg.zip file (approx. 1 MB).

Step 2. Unzip the epg.zip file.
Start the unzipping of the epg.zip file by double clicking on its name in for example the Windows Explorer; this results in unzipping, besides other files, the setup.exe program in the same folder.

Step 3. Start the setup program.
Start the unzipped setup.exe program by double clicking on its name in for example the Windows Explorer and follow the instructions on the screen.

Step 4. Remove files.
Remove the epg.zip file, the setup.exe file and the other files in for example the Windows Explorer. The name of the executable file to start ePerforationGauge is ePerforationGauge.Exe.

Latest Version

Follow the next two steps to install the latest version:

Step 1. Close the ePerforationGauge application.
When ePerforationGauge is currently in use, it should first be ended.

Step 2. Download het ePerforationGauge.exe bestand.
To download the latest version click here with the left mouse button, select the option Save this program to disk and select the folder where the application was installed (e.g. C:\Program Files\ePerforationGauge) in the Save As dialogue that follows to store the ePerforationGauge.exe file (approx. 200 kB).

Examples

Below are three the same stamps in different resolution and scale to try out ePerforationGauge. This stamp is the 22H, comb perforation 12½ : 12, 12½ ct. grey from The Netherlands.

resolution 150dpi, scale 100%

resolution 200dpi, scale 100%

resolution 200dpi, scale 150%

News

FAQ's

No faq's.