1941 NDH Nationalisation - Dubrovnik

Unfortunately, only a fragment, but still a nice example of 1941 NDH nationalisation on the "Young Petar" stamp...

1941 NDH Nationalisation, letter fragment with "Young Petar" 2 Din stamp, sent from Dubrovnik (24.V.41).

"Država Hrvatska" Type I rubber stamp enlarged.

1945 SARAJEVO, Postal stationery- Type III

Type III is the most scarce of all types and subtypes of the 1945 Sarajevo provisional issue cards. Only a few are known.

1945 Sarajevo local provisional issue, postal stationery, type III, unused.

The most notable difference in comparison to type I and type II is much larger distance between the bar and the five-pointed star. 

For the description for type I and II, please see post: http://alesstamps.blogspot.com/2014/07/1945-sarajevo-postal-stationery.html.

1942 NDH Red Cross, first day items

Four different first day items were prepared for this issue: two covers and two special commemorative cards.

Two different cancellations were used: black oval and red circle.

FDC with black oval cancellation.

FDC with red circle cancellation.

Small commemorative card.

Large commemorative card. Signed and numbered - No. 446 of  500. Unfolded!

1943 NDH Legionnaires, Ministerial album

In relation to the current situation in Ukraine - Croatian legionnaires have already fought on the Eastern Front.

1943 NDH Legionnaires, Ministerial album.

1943 NDH Legionnaires, Mi.107-110.

1944 DFJ, Vuk 2+3 stationery with message

I saw only two such postcards, both were unused and both with the same message on the back. I don't know if the message was prepared together with the original stationery or later with the DFJ provisional overprint.

1944 DFJ provisional issue, Vuk 2+3 din stationery with preprinted message on the back. Message was prepared for wounded soldiers in a military hospital in Smederevo.

HOWTO, Stamp Collecting Software

I just bought a new scanner and started to digitize my stamp collection. My goal is to create a database with each stamp individually. After one day of work, I can say that this will be very time consuming and tedious task. Unless I find a way to get myself 48 hours in a day, I need to do something to speed up this process.

Long time ago I worked on the development of image processing software, so I thought - maybe this will be a great opportunity to refresh my knowledge and have some fun too.

Let’s define our input as image with more or less randomly positioned stamps. 

Input image.

Step 1: Edge detection 

In theory, we know a number of edge detection filters, namely: homogeneity filter, difference filter, Sobel and Canny edge detection filter, etc. I decide to begin with the simplest one – the difference filter that finds edges by calculating the maximum difference between pixels in four directions around the processing pixel.

Edge detection - red line. 

Step 2: Quadrilaterals detection

Quadrilaterals (rectangles in our case) can be detected using Hough line transformation to find lines and then detect pairs of that lines that intersect with an angle of 90 degrees (approx.)

Quadrilaterals detection - yellow line.

Step 3: Extract individual item

Using quadrilaterals, we can calculate their bounding boxes and simply cut them out. All following steps are processed for all our cuts. 

Stamp extracted.

Step 4: Deskew (rotate) item

The rotation angle can be calculated from quadrilateral lines (as mean of all angles). Also Hough line transformation can be combined as a correction factor. In practice, getting angle is the most complicated operation in the whole process stack. But, when we have an angle, the rotation is trivial.

Stamp rotated.

Step 5: Fill background with transparent color

With last step we simply fill the background with transparent color. Flood fill algorithm is a way to go. Note that stamp image should be preserved in a format that supports transparency. My preferred format is PNG.

Stamp with transparent background.

I am now able to digitize my stamps for about fifty times faster! And, having images in such format brings a great deal of possibilities. Custom layouts are just one of them.

Row alignment layout.

Compact layout.

1945 MOSTAR, Shifted overprints

Normally, shifted overprints are considered as a random error and specialty. However, Mostar issue is not such a case! It is much more common to have stamp with a slightly shifted overprint than the centered stamp.

1945 Mostar local provisional issue, 30 / 3.50 Kn.

Centered overprints are much rarer than shifted ones.

Overprint displacement increases in proportion to the distance from the center of the sheet and have its maximum on all four corners (positions 1, 10, 91 and 100). 

1945 Mostar local provisional issue, 30 / 3.50 Kn, complete sheet.

Only nine complete sheets remained (one per Mi. 1, 2, 4, 5, 12, 13, 15, 16 and 17).