Qe4 Vs Qe4A

All,

I have been searching for a quality used copy of QE4a (not as easy as one may think given the small Catalogue value $22.50). Recently I purchased a stamp that was listed as QE4a online. Upon receipt, I questioned the color and after a short review they agreed that it was actually QE4 (Deep Green). I was pointed to a different stamp that was noted as being a true QE4a (Yellow Green). So I bought that copy.

Below are the stamps for comparison. The stamp on the left came from my collection and represents the Broken T variety. The color is clearly (at least to my eyes) the Deep Green QE4. The middle stamp is the one that was agreed to also be a QE4 and the one to the right was sold as QE4a. I recognize colors are never truly represented in scans/on-line but thought I would share this comparison for comment. Not much invested here (and happy with what I have) but I am interested in feedback on if you think these are properly identified. I don't see a great deal of difference in the middle and right stamp but maybe that is enough. I also included an overlap version for better comparison. Sorry scanner is older and 600 DPI is max and not cystal clear.






Thanks in advance for any comments.
Hobsun

the center and right stamps both look yellow green in color, all of the ones I have are the color of your left stamp

I'm in agreement with jim. The left looks quite different in color to my eyes.

EDIT: I should add, though, that there is a vague fuzziness to the right stamp.

Since you scanned them at the same time, we can compare them via computer. However, small jpeg images don't provide very accurate results.

I sampled a similar area of the middle and right hand stamp and put them into a web based color analyzer. Looking at the magnified areas, the two colors look quite different. The most noticeable difference in the histograms is the saturation plots.

DNA, if you were to include a comparable analysis of the left stamp you'd be my hero!

I've got to run off for a bit, but that won't take much time when I get back.

Cool beans!

Many thanks for the feedback. I agree that third entry seems blurry (especially in the close up) and I may have messed this up when I was cut and pasting the images over one another and in my compress for the size limits for uploading. They are all relatively nice clean/clear stamps in person.

DNA I may have to spend some time and learn about web based color analyzing. Do you any hints/advice/specific web sites I should visit to learn about this. Thanks again for your time.
Hobsun

Edited with better sampled right stamp. I think that I caught a bit of faint cancel so I sampled the upper left of it instead of the upper right corner.

The analysis of poor data sources necessitates that we don't look too deep into the results. However, that second peak on the saturation plot looks like it could be used at least as a rough identifier of a yellow green QE4a.

This histogram based analysis might prove inferior to another method of interpreting the sampled data. Regardless, the hypothesis would need to be tested using good data. That being 16 bit per channel non-compressed image files from a calibrated scanner and with expert opinion(s) providing a reference point upon which to base the findings.

Hobsun,
You're welcome. Give me some time to think about how to best present this complicated topic to you in a succinct and helpful manner.

Well, I failed on the succinct part but hopefully kept the jargon to a tolerable level.

The end goal of computer based color identification is to allow for anyone with a scanner to be able to identify the color of a stamp. The actual identification part will most likely be done using a specially written software program that analyzes a calibrated image of a stamp.

When a scan is taken, a raster image file is created where each pixel is represented by 3 numerical values. One each for red, green, and blue. These numbers by themselves mean nothing. When they are put into the context of a color space (reference #1 at bottom of page), they can be used by a computer to represent a defined color. This is then used by a computer to do things such as instruct the hardware of a monitor to display a certain color. So far I have found that the sRGB color space can represent all of the stamp colors that I have sampled which helps to simplify things.

The difficulty of using computers to sample and display colors accurately is due to the variations in material properties of the real world. Engineers and scientists have gone to great lengths to give us the stability of imaging and display devices which we enjoy today. Consumer grade computing equipment has finally become sufficient and affordable for widespread use. We now need only to adapt our home computers for use in shade identification.

The first step is accurately sampling the color of a stamp. This is possible with modern scanners if they are color calibrated. Calibration allows for the utilization of the concept of an absolute color space:

"A color space in which colors are unambiguous, that is, where the interpretations of colors in the space are colorimetrically defined without reference to external factors."(#2)

The scan needs to be taken with 16-bit sampling. 8-bit is adequate for representing and displaying color, but does not allow for the calibration process of consumer scanners. To retain all of the color information, the image file format must be not compressed. TIFF files are adequate for this.

Unfortunately not many image editing programs support 16-bit images and the ability to apply and convert color profiles. Higher level versions of Adobe Photoshop work. There are some others that are free which I'll provide links to if asked for.

At this point the color of an imaged stamp can be compared to another one created by any suitable hardware. Two images displayed next to each other on any decent monitor will show differences and similarities that are close to what would be seen by observing them physically next to each other.

The displayed images won't necessarily appear exactly as their color in the real world. Things like metamerism and monitor calibration will affect the displayed colors.(#3) However, one can display their stamp alongside a reference file of known stamp shades and be able to get a very good idea of what color theirs is.

Comparing a stamp physically set next to an image displayed on any monitor will not provide an accurate comparison. Monitor calibration does improve this, but does not eliminate the deficiencies of computing equipment to display color exactly as in the real world.

Comparing colors on a monitor is not ideal. Many people have deficiencies in color perception.(#4) Professional grade monitors and their calibration is expensive and still won't display color perfectly. Things like comparing histograms can aid in human based comparisons. Analysis methods such as using statistical algorithms removes the human variable.

Stamps are not actually identified by an exact color. They are put into categories. The color of a U.S. classic stamps is actually a combination of many different pigment particles of varying color and size. 9600 dpi is close to one ink particle per pixel. The 1861 3c stamp color expert Jack Daley bases his shade categorization on enhanced 9600 dpi scans by identifying such patterns by eye.

Computer software can be utilized to find and identify patterns in those variations. I am in the process of sampling as many stamps as possible that have been categorized by color experts. Though I am not the ideal person to develop analysis methods, I do try to find patterns and will share all of my leg work in collecting data with any who want to help.

Much needs to be done but the end goal of shade categorization being accessible by everyone with a suitable scanner is now technologically possible. When enough data has been collected for each stamp issue, then analysis methods must be developed to quantify meaningful patterns in the data. Then experts need to agree on category thresholds and how these computerized methods will fit into expertisation.

Here's the most comprehensive paper I have found:
Philatelic Shade Discrimination Based on Measured Color. David L. Herendeen, James A. Allen, Thomas Lera
http://postalmuseum.si.edu/research...orimetry.pdf

Here's some previous SCF threads:
https://goscf.com/t/44832
https://goscf.com/t/42317

Here's a web based Image Color Summarizer:
http://mkweb.bcgsc.ca/color_summarizer/?analyze
Choose the "Precision: extreme" option.

Here's a link to an accurate yet affordable scanner calibration target:
http://www.targets.coloraid.de/
Choose: R1 - IT 8.7/2 Reflective Scanner Target on Kodak Professional paper (incl. CD)
Shipping took about a week to me in the US from Germany and he even used some lovely stamps. Scroll down on the page for ordering information.
Calibrating a scanner with just this target is not simple, but I can provide instructions for a free method. There are alternatives that are easy but cost in the hundreds of dollars for a target and software package.


References:
1. https://en.wikipedia.org/wiki/Color_space
2. https://en.wikipedia.org/wiki/Color_management
3. https://en.wikipedia.org/wiki/Metam..._%28color%29
4. http://www.xrite.com/online-color-test-challenge

DNA,

I recognize this is not a trivial topic and it will involve trial and error and learn by doing activities. My goal would be to get a good sense of what it possible and how I might apply it to advance my stamp hobby interests/knowledge. I am looking for guidance on where to start, what to focus on and maybe what to avoid. Just words of wisdom to help me focus and see tangible results to build upon. Again, thanks in advance for your input.

Hobsun

Fascinating stuff! I'm watching too!

Edited my above reply.

As for what can be done with the tools we have now, use things like the web based color summarizer. You're looking for patterns. If you and someone else both calibrate your scanners, then you can compare stamp colors over the Internet. For other stuff, I might come up with some better ideas after ma brain becomes less fuzzy. Writing up that wall of text has drained me.

Ok I'm not expert here and do not claim to be one but the two stamps on the right appear to be of the dry printing QE4a and the stamp on left appears to be the regular QE4. If you look hard enough at the scans of the right two stamps you can see yellow outside and inside the vignette a little at least that is what I see and none of the stamp on the left. Also I do not think that the dry prints QE4a had the AT joined at the top or TA joined at the top. The stamp on the left is quite noticeable of a dark/deep green shade. This was what I was told back years ago but that person wasn't an expert neither he was a postal carrier. I guess you could break out the micrometer and measure the thickness or dunk them in some fluid. Like I said I am not an expert on stamps.
Newby

Hobson,

Here are my QE4's, maybe they will help you with your color question. If I understand Scott note correctly, QE4's were only wet printed.

QE4



QE4a



Eagle

Well, since this bit of information was not already here, I woke the dead.

After nearly a century of listing the first issues 1925 25 cent parcel post stamp after the 1928 printing version, the numbers, QE4 and QE4a stayed the same but the stamps were relisted in correct chronological order based upon release date. That mean after decades, the QE4 and QE4a change colors in the listing. Not all sellers and collectors got the memo and even if they did, they did not necessarily read it. Likewise old stack may not have been updated a nor purchased items marked as true (then) QE4a are now QE4 due to a Scott Editor decision.

Once you are certain of identifying the colors, next look for examples on special booklet paper.

If you want a beyond question example of the 1925 color buy a joined A-T or joined A-T and T-A example. Plate 17103 was not used in the second printing of the different color and is the only plate put into production with the joined varieties. Plate 17104 had them as well but was not used to produce stamps for post office sale.