Copy part of a bitmap image

[jeffg737]

I am running Liberty BASIC v4.03 under Windows 7, 64 bit.

I need a method to (1) load a bitmap image of size 8872 x 6472 pixels, (2) extract a series of sub-images from it, using the upper-left and lower-right coordinates (or some other method) to choose each sub-image, and (3) save each of the resulting sub-images to a file.

I have tried the techniques described at libertybasiccom.proboards.com/thread/1165/large-image-outside-graphic-window, but I am not getting the desired results. Any help or advice would be greatly appreciated. Thank you all.

[Rod]

The one limitation is that the bmp you want to extract must be visible on your screen. So imagine you have loaded this large bmp. You have a smaller graphicbox to display it. This graphicbox cannot be larger than your visible display.

Now simply draw the large bmp to the smaller graphicbox but set the coordinates to suit. So x and y will be negative values to skew the portion you want to see into view.

-500 -500 will skew a 1000x1000 bmp to display its mid position in a much smaller graphicbox.

Once displayed you can getbmp save bmp etc.

[Walt Decker]

UNTESTED!!!

'

STRUCT tRect, _
 X  AS LONG, _
 Y  AS LONG, _
 X1 AS LONG, _
 Y1 AS LONG

GRAPHICBOX #DMO.GFX, 0, 0, 200, 200
OPEN "DEMO" FOR WINDOW AS #DMO

GfxHndl = HWND(#DMO.GFX)
CALLDLL #user32, "GetClientRect", GfxHndl AS ULONG, tRect AS STRUCT, RetVal AS VOID

GfxWide = tRect.X1.struct
GfxHigh = tRect.Y1.struct

'ASSUMING THAT THE BITMAP IS 1000 X 1000

LOADBMP "DMOBMP", YourBitmapName

NumSectionsWide = INT(1000 / GfxWide) '<--- number of sections in bitmap
NunSectionsHigh = IND(1000 / GfxHigh)

'<===== DISPLAY TOP LEFT CORNER OF BITMAP ===>
Sectionx = 0
Sectiony = 0
X = -1 * Sectionx * NumSectionsWide  '<--- calculate which portion of
Y = -1 * Sectiony * NumSectionsHigh  'bitmap to display

PRINT #DMO.GFX, "DOWN"
PRINT #DMO.GFX, "DRAWBITMAP DMOBMP";X;" ";Y
PRINT #DMO.GFX, "FLUSH"

CALLDLL #kernel32, "Sleep", 1000 AS LONG, RetVal AS VOID

'<===== DISPLAY TOP PORTION OF BITMAP ===>

Sectionx = 1
X = -1 * Sectionx * NumSectionsWide

PRINT #DMO.GFX, "DOWN"
PRINT #DMO.GFX, "DRAWBITMAP DMOBMP";X;" ";Y
PRINT #DMO.GFX, "FLUSH"

CALLDLL #kernel32, "Sleep", 1000 AS LONG, RetVal AS VOID

'<===== DISPLAY LEFT SIDE OF BITMAP ===>

Sectiony = 1
Y = -1 * Sectiony * NumSectionsHigh
X = 0
PRINT #DMO.GFX, "DOWN"
PRINT #DMO.GFX, "DRAWBITMAP DMOBMP";X;" ";Y
UNLOADBMP "DMOBMP"
WAIT
'

There are actually better API functions to do the above.

[Rod]

We don’t need API to achieve this. Native loadbmp, drawbmp and bmpsave are all that’s needed.

[Walt Decker]

I did not say that API was needed. I said there are better ways using API.

[Rod]

There are even better machine code solutions!

[jeffg737]

Thank you for your reply.

I do not need to see my original loaded 8872 x 6472 pixel bitmap image or any of the copied bitmap images. I just need to copy a part of my original bitmap image from specified coordinates x1,y1 (upper left hand corner) and x2,y2 (lower right hand corner), and then save this copy to a file, all unseen.

[tsh73]

I was thinking 9000x6500 is too big for LB but
I made that bitmap in Paint
draw something on it
and LB LOADBMP it
and DRAWBMP with offset after
I change offset, press Draw - it works, several times (until bored)
(but a memory usage show 520 Mb
and before I added CLS it crashed with Out Of Memory on second Draw
)

So I can confirm - it does work. At least for me.

Put path to your big bitmap in [Load] section and try.


'Form created with the help of Freeform 3 v07-31-2015
'Generated on Nov 10, 2022 at 00:25:32


[setup.main.Window]

   '-----Begin code for #main

   nomainwin
   WindowWidth = 520
   WindowHeight = 610
   UpperLeftX=int((DisplayWidth-WindowWidth)/2)
   UpperLeftY=int((DisplayHeight-WindowHeight)/2)


   '-----Begin GUI objects code

   graphicbox #main.graphicbox5,   7,  67, 500, 500
   button #main.button1,"Draw",[Draw], UL, 145,  17,  96,  25
   TextboxColor$ = "white"
   'put offset in a bitmap here
   textbox #main.txtX,  10,   7, 100,  25
   textbox #main.txtY,  10,  32, 100,  25
   button #main.button6,"Load",[Load], UL, 260,  17,  96,  25

   '-----End GUI objects code

   open "untitled" for window as #main
   print #main.graphicbox5, "down; fill white; flush"
   print #main, "font ms_sans_serif 10"
   print #main, "trapclose [quit.main]"

   #main.graphicbox5, "line 0 0 500 500"
   #main.graphicbox5, "line 0 500 500 0"
   #main.graphicbox5, "getbmp bmp 0 0 500 500"

[main.inputLoop]   'wait here for input event
   wait



[Draw]   'Perform action for the button named 'button1'

   #main.txtX "!contents? x$"
   X=val(x$)
   #main.txtY "!contents? y$"
   Y=val(y$)
   #main.graphicbox5 "cls"
   #main.graphicbox5 "drawbmp bmp ";0-X;" ";0-Y

   wait


[Load]   'Perform action for the button named 'button6'
   loadbmp "bmp", "C:\Temp\60k.bmp"    'made 9000x6500 bitmap with Paint

   'Insert your own code here

   wait

[quit.main] 'End the program
   close #main
   end



[tsh73]

I just need to copy a part of my original bitmap image from specified coordinates x1,y1 (upper left hand corner) and x2,y2 (lower right hand corner), and then save this copy to a file, all unseen.

Well, native LB could load, show at any offset/save any visible parts.
Obviously "all unseen" requires different approach.

[tsh73]

If I had such a need I would try to use already written program first
ImageMagick
This feature looks like one fitting your problem.
imagemagick.org/script/command-line-options.php#extract

[Walt Decker]

I do not think this will work, but

1) create a graphic box without border off your window
2) calculate the number of sections in both horizontal an vertical directions
3) calculate the negative x, y offset for each section
4) load the bitmap using LOADBMP "YOURTAG", BMP PATH AND NAME
5) draw the bitmap to the graphic box
6) get the result from the graphic box using "GETBMP YOURTAG 0 0 ";Gfxwide;" ";Gfxhigh
7) save the bitmap
8) unload the bitmap

If that does not work you will have to use User32.dll functions and either or both gdi32.dll/gdiplus.dll functions to accomplish the task.

[tenochtitlanuk]

Old hands on the Forum will know I do such processing with ImageMagick. Straight off the 'net I found this code line...

convert 8872x6472.bmp +repage -crop 1000x1000 tiles\tile%04d.bmp worked for me from the command line.

I use LB under Linux/Wine. LB can call ImageMagick ( see the examples on my website)

But simpler to do it yourself directly. I create a 8872x6472.bmp colour gradient file.

Image shows the images the above command created in a few seconds- all the possible tiles. Lots of help online for how to select a particular single tile...



INCIDENTALLY- tsh73 (anatoly) beat me to giving a native LB code example. My immediate reaction was why not use UpperLeftX and UpperLeftY to offset the graphic window off-screen, but with my setup at least LB doesn't use negatives. And I had thought it did!

EDIT Ninja'd by Anatoly...

[Rod]

Nice. It would of course be possible to manipulate the file directly and extract sub image data. The data can easily be written back out as a .bmp. There are several examples of direct .bmp file manipulation posted on the forum.

Essentially you read the header of the main file, decide how the sub images are to be sized and create a header for that size. Then suck out the image data and write it out with the new header.

It gets complicated if the input image can change format. If it is always going to be a 24 bit bmp then it gets a little easier. But how are the sub image sizes to be decided?

With this method there are less memory issues and no graphics display to deal with, it is all hidden.

[Walt Decker]

Here is a little dll I put together from bits from other dlls. There are only 2 functions in it, both are shown in the sub.

The zip contains:
SPLIT_000._BAS
SPLITGFX.DLL

BLOCKS.PNG

SPLITTER.ZIP (54.36 KB)

[tenochtitlanuk]

Could you clarify what the results should be? For me on Linux/Wine/LB I got the repeated set of sub-images shown below. Is that what is supposed to happen?
I EXPECTED images 75x75 but not the row- repetition. nor for the edge cases to be as shown, since 1000/75 is non-integer. Sorry, I don't get it. My IM demo did what I expected.