How is this technique implemented?
I noticed that they(like Bartender) don't directly concatenate commands like ZPL (etc.).
And also they don't use bitmap(GDI,GDI+ images) transfer to printer-driver.
Printer-based Serialization In print jobs that include serial numbers, many printers can accept a starting value and the incremental
step size. When you use this printer-based serialization, you can
print a large number of serialized items without having to send any
data after the first label.
Printer-based Barcodes Printers that have built-in barcode functionality make it possible for software programs to request
complex barcodes by using simple text strings (such as “1234”). This
process is much faster than sending bitmap images (or pictures) of
barcodes that consume hundreds or thousands of extra bytes per printed
item. (When you use software other than BarTender, our driver fonts
give you some limited functionality.)
Printer-based barcodes are, as you mention, barcodes that have the symbology / definition stored in the printer firmware. Much like a DLL that you give "12345" and as a result gets a bitmap, an SVG file etc etc.
Many modern label printers know a bunch of common symbologies such as EAN, DM, QR, UPC and similar.
The benefit is obviously that it makes transfer of data much more efficient. Instead of sending a (large) image for every print, the software just sends initial definition (layout, symbology choice and options, ..) + the value needed. Taken to the next level, the printer could receive metadata such as "take this layout, make 500 labels, and in the barcode start at 1, increase 1 every label".
Some disadvantages are
is that the appearance is left to the firmware designer of the printer firmware
There may be less coordination between what's being designed and what's being printed, although typically the driver for the printer should adress this.
The printer firmware may not be updated if the barcode symbology specifications has been updated
The printer firmware may contain only a subset of the barcode definition
In short, simplificy vs freedom of parameters and appearance.
How it is technically implemented (at printer end, from receiving the number to drawing the actual barcode) is probably out of scope for this forum.
Example specification (in newer printer model)
Looking at a random Zebra Printer (ZT600) the built-in barcodes covers nearly every use:
1D symbologies
Code11, Code39, Code93, Code128 (all subsets),
UCC, ISBT, UPC, EAN 8 / 13, UPC/EAN extensions,
Plessey, Postnet, 2of5, Logmars, MSI, Codabar and Planet Code
2D symbologies
codablock, PDF417, Code49, Datamatrix,
QR, TLC39, MicroPDF, RSS14 +composite and Aztec.
When you print an element on a label (barcode or text) you can do that by sending a graphic field or by instructing the printer to pick up the element internally and build the element with the configuration you need.
For example, in case you want to print a text, the ZPL command will include the font you want to use, vertical and horizontal size, position of the text and so on.
In the case of a barcode, the barcode selector contained in the ZPL command, will automatically recall the .BAR file stored in the Z memory, which contains the instructions for the printer to build the barcode, then, in the same command and likewise for the text, you have also provide the size of the barcode (usually it's a ratio between the narrow and the bold line), the position, the human readable line and so on.
The graphic method is used for example when a font which is not stored on the printer memory is used: the printer doesn't recognize the font and so it can't build the text, so the print can happen only after a conversion of the text field into a graphic field. This works well with text fields, but the barcodes can have quality issues as, due to how a thermal printers physicall works, the lines of a barcode can be printed like a sort of saw. Moreover you can't see or edit the data since the code is basically unreadable, that's why it's impossible to send serialized data, unless you use a software.
The element printing is not affected by this type of quality issues and allows you to edit the data.
If you want to see the difference, try to use zebradesigner and print to file a label with a barocode. When you select a barcode, you can choose to print it as a graphic or to use the printer element and you'll see that the .prn files will contains different data.
This is what you get using the printer element (128 barcode containing 123456789012)
https://justpaste.it/66gvp
and this is the same barcode printed as graphic field
https://justpaste.it/27abu
I'm trying to create 2D barcode images with iOS and CoreImage using a CIFilter for CIAztecCodeGenerator. Depending on the length of the text and the error correction level settings, CIFilter.outputImage sometimes returns nil.
The following message is printed on the console only:
Unable to create barcode. The message is too large for an Aztec
barcode.
A similar message will be printed when using CIQRCodeGenerator.
Is there a way to catch this kind of error for CIFilter in code or find out in advance if the text will be too long to be processed?
Thank you very much for any suggestions!
The maximum size of the data depends on the correction level and also on the type of message that you want to encode. For example if your text only have numbers then a different encoding is used to put that data in the barcode and more characters will be allowed. You cannot really detect that specific error but you can always just check if the result was nil. If it was nil then probably beacuse message was too long.
According to documentation at https://developer.apple.com/library/archive/documentation/GraphicsImaging/Reference/CoreImageFilterReference/index.html#//apple_ref/doc/filter/ci/CIAztecCodeGenerator :
The full-size format can store up to 1914 bytes of message data
(including correction) in up to 32 layers, producing a barcode image
sized no larger than 151 x 151 pixels.
Also at https://help.accusoft.com/BarcodeXpress/v13.2/BxNodeJs/aztec.html you will find this 1914 bytes value. So probably you could assume that anything that is not larger than 1914 bytes should be successfully encoded by CIAztecCodeGenerator, but encoding anything above that size could fail.
I am facing the same problem as described here when trying to decode a frame on iPad Pro OS v14.3 (I am also using Olivia Stork's example):
25% of the picture data is decoded correctly, the rest of the picture is just green.
The decoded image on iPad Pro OS v14.3 looks like this (the image was converted and saved in the decoder callback as described here, so it's not just a displaying problem).
The original image looks like this.
The image is encoded with NVIDIA NVENC (Media Foundation) on Windows10.
I searched the frame picture data for additional 4-Byte NALU start codes as described in the link, but there are only the three expected ones for SPS, PPS and IDR picture data.
I have another Media Foundation decoder application running on Windows10 which can decode the frames from exactly the same source correctly.
I am struggling for days now finding the cause of the problem.. anyone any ideas?
Thanks in advance. Rob
-
EDIT 2021-01-11:
I figured out that there are actually three additional 3-byte start codes (0x000001) within in the IDR picture data block of NALU type 5.
I tried to replace these start codes with the length of the following data block (big endian), as described here, but with the same result.
I also tried adding Emulation Prevention Bytes (0x000001 => 0x000301) as described here, but that also made no difference.
Maybe I am mislead and these start codes have nothing to do with the issue.. at least they are not just random image data, because they always appear at the same position (index) in the picture data block. Currently I am running out of ideas.. any hint anybody?
-
EDIT 2021-01-14:
I figured out a few more things:
Out of sheer lack of ideas I copied the picture data followed after the last start code at the beginning of the block (right after after the 4-Byte NALU start code).
I had expected - if that would work at all - to see the last quarter of the original image at the top of the decoded image, but to my surprise the decoded image looked like this.
I tried the same with the picture data coming after the second and third start code, and the decoded image looked like this and this:
The image data is decoded correctly and it is even at the correct position (compare to original image).
Even if I strip off all 3-Byte start codes and copy the picture data concatenated after the 4-Byte start code, it's the same result, only 25% of the image is decoded. So the additional 3-Byte start codes are apparently not the problem. There must be some setting somewhere which tells the decoder to only decode 25% of the image. I would tip on the CMVideoFormatDescription, but as far as I can see it looks okay.
I am also wondering how the decoder knows where to display the different picture data blocks. Either there is an offset defined somewhere within the picture data or the xy-position of every pixel is added by the encoder somehow..
I managed to find the cause of the problem: The 3-Byte start codes in the IDE picture data block must be replaced by 4-Byte start codes.
So first replace all 3-Byte start codes by 4-Byte start codes.
Then replace the 4-Byte start codes with the length of the following data block (big endian). The slices should be arranged like this (as mentioned here by 'Blackie'):
[4byte slice1 size][slice1 data][4byte slice2 size][slice2 data]...[4byte slice4 size][slice4 data]
Remember to not include the start code length in slice size.
After changing that, my frame was completely displayed.
By the way:
The information where to display the different picture data blocks is specified in the header data of each NALU (parameter 'first_mb_in_slice').
There is a very good c# example here how to extract the NALU header data. You can almost copy it 1:1.
I have to parse some Lab Reports and I am using Tesseract to extract data from them. I have encountered an issue that Tesseract does not correctly recognize the text if I pass entire page's image. But if I pass a small subsection of page (from Test Report covering the entire table till *****) it is able to read all the text correctly.
In the formal case (when I pass the entire image) it produces some random text output of English words which do not make sense. Part of text is as follows:
Command I ran: tesseract -l eng report.png out
Refierence No : assurcAN, 98941-EU
5:er Nu (SKU) , 95942, 95943
Labelled age gwup “aw
Quamny 20 pweces
Fackagmg pmwosd Yes
Vendor
Manmamurer
But when I pass the subsection, I get accurate results.
What might be the issue here? How do I fix it?
See the sample report image:
I need to parse the USDL (U.S driving Licence) barcodes which is in PDF417 format. I almost got the parsing, but when parse a barcode from ohio state. It shows unrecognized barcode information.
o/p-OHLOVELAND^NEAL$RAYMOND$E$^11947 FOXGATE
WAYGDGACDBJBBBBJBFGXBGAGBJHBAGCBBAEFBEABIJA 3 1
BFBACBA1.:70
I don't get any idea to parse this output format.
I tried different Barcode scanner available in online,but no one works fine.
Is there any idea to parse this result?