How to save a picturebox's image to a .PNG file? (VB6)
in [Visual Basic]
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From: Nando on 1 Aug 2010 15:17 Hi all! I have a little program (written in VB6) that saves the image in a picturebox to a BMP file. The problem is that BMP files are several megabytes in size and do not support DPI (dots-per-inch) information for printing. I have turned to the PNG format which provides lossless compression (files are only few kilobytes) and includes DPI information. But how do I save the image in a picturebox to a PNG file? Thanks in advance!
From: Mike Williams on 1 Aug 2010 16:39 "Nando" <hightech(a)att.net.no.to.sp.am> wrote in message news:uflaC5aMLHA.2100(a)TK2MSFTNGP06.phx.gbl... > Hi all! I have a little program (written in VB6) that saves the > image in a picturebox to a BMP file. The problem is that BMP > files are several megabytes in size and do not support DPI > (dots-per-inch) information for printing. I have turned to the > PNG format which provides lossless compression (files are > only few kilobytes) and includes DPI information. The png format will give you those kind of lossless compressions (50:1 or even more) on simple images, such as line drawings with filled sections and graphs and other images with a limited number of colours and many small or large areas of a solid colour, but the png lossless compression of a tpyical photo will be much less, perhaps in the order of 2:1 or something of that nature. So, if your images are of the kind I first mentioned then png is definitely one way to go if you want high compression, but if they are typical photos (and if compression is your main concern) then the lossy but still quite good compression of a jpg might be more suitable (although the fact that png can give you lossless compression on photos might be exactly what you want if compression is not your main concern). As far as DPI information in an image file is concerned, that's a moot point that I won't go into here because I sometimes get into lots of trouble from various people for writing too much waffle :-) > But how do I save the image in a picturebox to a PNG file? I reckon GDI+ is probably your best bet. Have a look at: http://www.vbaccelerator.com/home/vb/code/vbmedia/using_gdi_plus/Reading_and_Writing_JPG__PNG__TIF_and_GIF_Files/article.asp Mike
From: MikeD on 1 Aug 2010 16:56 "Nando" <hightech(a)att.net.no.to.sp.am> wrote in message news:uflaC5aMLHA.2100(a)TK2MSFTNGP06.phx.gbl... > Hi all! I have a little program (written in VB6) that saves the image in a > picturebox to a BMP file. The problem is that BMP files are several > megabytes in size and do not support DPI (dots-per-inch) information for > printing. > > I have turned to the PNG format which provides lossless compression (files > are only few kilobytes) and includes DPI information. > > But how do I save the image in a picturebox to a PNG file? VB6 does not natively support the PNG format. Look for an OCX or DLL that does (sorry, I personally don't know of any or I'd suggest one). Or, I suppose you could search the Internet for the PNG format's file spec and write the file yourself. Finding an OCX/DLL would probably be a lot easier, and I'd be willing to bet there are free ones out there that shouldn't be too hard to find. -- Mike
From: Shotgun Thom on 1 Aug 2010 23:18 Nando... There are plenty of free resources out there for saving an image in the PNG format. One is the Free Image open source DLL. It even has VB6 examples. It's open source and available at: http://freeimage.sourceforge.net/sourcecode.html Even Microsoft provides that ability with the Windows Image Acquisition Library (WIA) found here: http://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=a332a77a-01b8-4de6-91c2-b7ea32537e29 Mike Williams also gave you a good resource at vbAcclerator. And, btw, Mike.... one man's waffle is another man's treasure. I usually learn something with your "waffles". Don't stop now! Tom
From: Horst Heinrich Dittgens on 2 Aug 2010 10:08
> And, btw, Mike.... one man's waffle is another man's treasure. I > usually learn something with your "waffles". Don't stop now! what I would like to underwrite, too! |