B4J Question QRCode generator: Save png file as real bw (1 Bit)

[KMatle]

I'm generating QCodes with Erel's QRCode generator. Later I print these on a POS printer (via file). Here the images are distorted. In Xnview I've seen that the png files have up to 57 colours (though all used colours are black and white). After conversion (via XnView)to 1 Bit (pure bw) the POS printer prints like a charm.

QRView.SetBitmap(QR.Create(QRString))
Dim im As Image  = QRView.Snapshot
Dim Out As OutputStream = File.OpenOutput(File.DirApp, "qr.png",False)
im.WriteToStream(Out)
Out.Close

Q: How do I save the png file as a "real" bw file?

 

[Johan Schoeman]

Thread 'Otsu Thresholding - binarization of images' https://www.b4x.com/android/forum/threads/otsu-thresholding-binarization-of-images.44406/

Not sure this will help....

 

[Pendrush]

You can also try:

jMagicImage - Read exif and metadata data, convert, compress image, also some basic image filters

Original libarary: https://github.com/magiclen/MagicImage jMagicImage is a B4j (wrapper) library for image processing. It can support many formats of images in Java programs and provide common functions to make adjustments to the image. After you finish adjusting your images, you can export...

www.b4x.com

 

[JordiCP]

My one-cent

The several colors that you see (grayscale levels) are due to expanding the B4XBitmap returned by QR.create(QRString) to fit into QRView, which has different dimensions than the original bitmap. Anti-aliasing does the rest.

If, instead, you save the same Image returned by QR.Create, it will only have white and black pixels (event if it is saved in 32-bit format)

(Using Erel's example)

' Don't do this
    Dim im As Image  = ImageView1.Snapshot    '<-- Here you are taking the snapshot of the visualization of the bitmap, which is anti-aliased.
    Dim Out As OutputStream = File.OpenOutput(File.DirApp, "qr.png",False)
    im.WriteToStream(Out)
    Out.Close

Result (anti-aliased, grayscale transitions)

'Do that
    Dim imOK As Image  = qr.Create("QR with B4X!!!")
    Dim OutOK As OutputStream = File.OpenOutput(File.DirApp, "qrOK.png",False)
    imOK.WriteToStream(OutOK)
    OutOK.Close

Result (not anti-aliased since it is the originally generated bitmap)

 

[AnandGupta]

at the risk of receiving the wrath of the experts, i think you will find the main problem is android doesn't support 1-bit bitmaps.

I think KMatle is asking fort B4J solution.

 

[drgottjr]

I think KMatle is asking fort B4J solution.

Ich Esel!

 

[KMatle]

Please start a new thread for the Esel (donkey) topic