Re: How to convert image from Format1bppIndexed to Format24bppRgb?

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Maybe I'm completely missing your point (sorry if I am), but aren't I
doing exactly what you're stating I should do?

//In the case of conversion from any type of image to a 24 or 32 bit
//image you just need to create a bitmap of the correct size

Dim oRaster As Image = Image.FromFile(sRasterPath)
Dim bm As Bitmap = New Bitmap(oRaster.Width, oRaster.Height,
PixelFormat.Format24bppRgb)

//obtain a Graphics object for the new image and draw the old image
//onto it using DrawImage

Dim g As Graphics = Graphics.FromImage(bm)
Dim rect As Rectangle = New Rectangle(0, 0, bm.Width, bm.Height)
g.DrawImage(bm, rect, 0, 0, bm.Width, bm.Height, GraphicsUnit.Pixel)

Or are you saying that this SHOULD work in theory, but since my images
are so large - it's just not going to work for me? Thanks a lot Bob, I
really appreciate you taking the time to answer questions from a very
confused person! :)


"Bob Powell [MVP]" <bob@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message news:<uqvKdWLSFHA.3336@xxxxxxxxxxxxxxxxxxxx>...
> Clone is for creating a copy so it stands to reason that the clone of a 1bpp
> bitmap will also be a 1bpp bitmap.
>
> To copy a bitmap to another format you have to convert the pixels.
>
> In the case of conversion from any type of image to a 24 or 32 bit image you
> just need to create a bitmap of the correct size, obtain a Graphics object
> for the new image and draw the old image onto it using DrawImage. In the
> case of conversion to any indexed type you need to understand the pixel
> format, lock the new image using lockbits and convert the data pixel by
> pixel.
>
> --
> Bob Powell [MVP]
> Visual C#, System.Drawing
>
> Find great Windows Forms articles in Windows Forms Tips and Tricks
> http://www.bobpowell.net/tipstricks.htm
>
> Answer those GDI+ questions with the GDI+ FAQ
> http://www.bobpowell.net/faqmain.htm
>
> All new articles provide code in C# and VB.NET.
> Subscribe to the RSS feeds provided and never miss a new article.
>
>
>
>
>
> <blackcarrera@xxxxxxxxxxx> wrote in message
> news:1114325862.445661.59610@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> > Thanks Bob - one last question for you...
> >
> > When I use clone() on bitmap bm, the resulting bitmap bm2 is still 1bpp
> > even though I've specified that I want it to be 24bpp - also a memory
> > problem? Since no error is generated, should I just assume that instead
> > of trying to create the 24bpp and generating an "out of memory" error,
> > the resulting bm2 just takes on the pixel format of the cloned bm?
> >
> > 2)
> > bm2 = bm.Clone(New
> > Rectangle(0,0,bm.Width,bm.Height),PixelFormat.Format24bppRgb)
> >
> > -> the new bitmap bm2 is Format1bppIndexed, not Format24bppRgb
> >
> > Thanks again for all your help!!
> >
> > Bob Powell [MVP] wrote:
> >> The size of the image file has no bearing on the amount of memory you
> > need
> >> to represent that file internally. A JPEG image is compressed and
> > when the
> >> image is read and turned into a raster the memory requirements are
> > well
> >> known and fixed. The size of a 1bpp image is 24 times smaller than
> > the
> >> equivalent 24bpp image in memory.
> >>
> >> If your file has 10,000 by 10,000 pixels that will require
> > 3*10000*10000
> >> bytes (300 million bytes). To store an Argb file would be 400 million
> > bytes.
> >>
> >> Given that your system might be using a considerable chunk of the 1
> > gig
> >> available and the image might require 400 megs as well you're running
> > fairly
> >> close to the limits.
> >>
> >> Paging of virtual memory is slow and not really designed for huge
> > amounts of
> >> memory that images require so that will further restrict the system.
> >>
> >> You're correct in saying that the code looks fine. If the image were
> > smaller
> >> it'd work just fine. When the system says you're out of memory
> > believe it.
> >> It knows.
> >>
> >> Add a bunch of 1 gb simms and things will be happier.
> >>
> >> --
> >> Bob Powell [MVP]
> >> Visual C#, System.Drawing
> >>
> >> Find great Windows Forms articles in Windows Forms Tips and Tricks
> >> http://www.bobpowell.net/tipstricks.htm
> >>
> >> Answer those GDI+ questions with the GDI+ FAQ
> >> http://www.bobpowell.net/faqmain.htm
> >>
> >> All new articles provide code in C# and VB.NET.
> >> Subscribe to the RSS feeds provided and never miss a new article.
> >>
> >>
> >>
> >>
> >>
> >> "JY" <blackcarrera@xxxxxxxxxxx> wrote in message
> >> news:bc38f5ee.0504221152.4f7523d@xxxxxxxxxxxxxxxxxxxxx
> >> > All of my images that are 24bppRgb are also about 41MB in size,
> >> > 10000x10000 pixels are fine when I make calls to FromImage,
> > DrawImage,
> >> > etc. It's only when I try to convert the 1bpp to 24bppRbg that I
> > run
> >> > into the problem when I make calls to DrawImage (in the process of
> >> > trying to convert pixel formats)...
> >> >
> >> > I also have 1GB RAM so I don't really think that I'm literally "Out
> > of
> >> > memory" (how did you calculate that I would need 128MB?)
> >> >
> >> > Any other ideas? My code looks ok?
> >> >
> >> > Thanks again for your help!!
> >> >
> >> >
> > -------------------------------------------------------------------------------
> >> >
> > -------------------------------------------------------------------------------
> >> > That suggests to me that it's a bit large then.. If the image was
> >> > square
> >> > it'd be 6556 pixels on a side. To make a 24 bit per pixel image
> > you'd
> >> > require 128 megabytes of memory.
> >> >
> >> > There is a possibility that the resulting image is indeed too large
> >> > for the
> >> > machine.
> >> >
> >> > --
> >> > Bob Powell [MVP]
> >> > Visual C#, System.Drawing
> >> >
> >> > Find great Windows Forms articles in Windows Forms Tips and Tricks
> >> > http://www.bobpowell.net/tipstricks.htm
> >> >
> >> > Answer those GDI+ questions with the GDI+ FAQ
> >> > http://www.bobpowell.net/faqmain.htm
> >> >
> >> > All new articles provide code in C# and VB.NET.
> >> > Subscribe to the RSS feeds provided and never miss a new article.
> >> >
> >> >
> >> >
> >> >
> >> >
> >> > "JY" <blackcarrera@xxxxxxxxxxx> wrote in message
> >> > news:bc38f5ee.0504220621.6e05e418@xxxxxxxxxxxxxxxxxxxxx
> >> >> Thanks for your response Bob... The 1bpp mage is about 41MB
> >> >>
> >> >> "Bob Powell [MVP]" <bob@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in
> > message
> >> >> news:<uKzQARsRFHA.3560@xxxxxxxxxxxxxxxxxxxx>...
> >> >>> How big is the 1bpp image?
> >> >>>
> >> >>> --
> >> >>> Bob Powell [MVP]
> >> >>> Visual C#, System.Drawing
> >> >>>
> >> >>> Find great Windows Forms articles in Windows Forms Tips and
> > Tricks
> >> >>> http://www.bobpowell.net/tipstricks.htm
> >> >>>
> >> >>> Answer those GDI+ questions with the GDI+ FAQ
> >> >>> http://www.bobpowell.net/faqmain.htm
> >> >>>
> >> >>> All new articles provide code in C# and VB.NET.
> >> >>> Subscribe to the RSS feeds provided and never miss a new article.
> >> >>>
> >> >>>
> >> >>>
> >> >>>
> >> >>>
> >> >>> "JY" <blackcarrera@xxxxxxxxxxx> wrote in message
> >> >>> news:bc38f5ee.0504211045.101b6cc5@xxxxxxxxxxxxxxxxxxxxx
> >> >>> > Hi,
> >> >>> > I'm trying to convert an image with PixelFormat
> > Format1bppIndexed
> >> > to
> >> >>> > Format24bppRgb. I keep getting the "Out of memory" message.
> >> >>> >
> >> >>> > Here's what I've tried:(
> >> >>> >
> >> >>> > (where bm.PixelFormat is Format1bppIndexed)
> >> >>> > 1)
> >> >>> > bm2 = New Bitmap(bm.Width, bm.Height,
> > PixelFormat.Format24bppRgb)
> >> >>> > g2 As Graphics = Graphics.FromImage(bm2)
> >> >>> > g2.DrawImage(bm, subRect, 0, 0, bm.Width, bm.Height,
> >> >>> > GraphicsUnit.Pixel)
> >> >>> >
> >> >>> > -> get "Out of memory"
> >> >>> >
> >> >>> > 2)
> >> >>> > bm2 = bm.Clone(New Rectangle(0, 0, bm.Width, bm.Height),
> >> >>> > PixelFormat.Format24bppRgb)
> >> >>> >
> >> >>> > -> the new bitmap bm2 is Format1bppIndexed, not Format24bppRgb
> >> >>> >
> >> >>> > Any ideas? I don't necessarily need the image to be
> >> > Format24bppRgb - I
> >> >>> > just need to be able to use the function "Graphics.FromImage"
> > (so
> >> > it
> >> >>> > could be Format16bppRgb555, etc). Any help will be greatly
> >> >>> > appreciated!!
> >
.

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