Print Page - draw image pixel_by

Title: draw image pixel_by_pixel (Solved)
Post by: onugl on 2008-Jul-20

I'm tryng to draw an image pixel by pixel, but I don't know how to do it :whistle:

This is my ugly code

Code (glbasic) Select

// --------------------------------- //
// Project: pic_pixelTopixel
// Start: Sunday, July 20, 2008
// IDE Version: 5.322


SETSCREEN 640, 480, 0   // MODO GRAFICO
LIMITFPS 60

SCREEN_PIXEL("d:/test.png", 640, 480)


FUNCTION SCREEN_PIXEL:image$, zwidth, zheight

	LOCAL  gx, gy,  pixel, INCR, c, graphseg = 0;

	LOADSPRITE image$, 1
	
	CREATESCREEN 0, 13, zwidth, zheight
	
	USESCREEN 0
	DRAWSPRITE 1,0,0
	
	FOR gy = 0 TO zheight - 1
		FOR gx = 0 TO zwidth - 1
			USESCREEN 0
			pixel= GETPIXEL(gx, gy)
			USESCREEN -1
			USEASBMP
			SETPIXEL gx, gy, pixel
			SHOWSCREEN
		NEXT
	NEXT

ENDFUNCTION

Thank you in advance

Title: Re: (My) stupid question (draw image pixel_by_pixel)
Post by: PeeJay on 2008-Jul-20

There's no such thing as a stupid question (but there are stupid answers, usually given by me :D)

The easiest way to do this is using the POLYVECTOR command, where you can display part of an image - saves all the messy screen bits.

Hope that helps ....

Title: Re: (My) stupid question (draw image pixel_by_pixel)
Post by: onugl on 2008-Jul-21

=D Thank you PeeJay, I'll see POLYVECTOR command.

I need to convert pixels to black&white before to put in the screen

I have now this code, but while it is putting pixels, the screen is degradated

Code (glbasic) Select

// this code will put an image pixel by pixel
// but the image is being degradated while pixels is putting in screen

SETSCREEN 640, 480, 0   // MODO GRAFICO
LIMITFPS 60


ZX_SCREEN("d:/test.png", 640, 480, 0,0, 2)
MOUSEWAIT

FUNCTION ZX_SCREEN:grafico$, zwidth, zheight, x, y, velocidad
	LOCAL  gx, gy,  pixel
	
        BLACKSCREEN
	GRABSPRITE 2, 0,0, zwidth, zheight  // create a black sprite
	
	LOADSPRITE grafico$, 1
	
			
	FOR gy = 0 TO zheight - 1
		
		FOR gx = 0 TO zwidth - 1
			
			DRAWSPRITE 1, 0,0  // draw original image
			
			pixel = GETPIXEL(gx, gy)
			
			IF pixel > RGB(255,255,255)/2
				pixel = RGB(255,255,255)   // white
			ELSE
				pixel = RGB(0,0,0)            // black
			ENDIF
			
			DRAWSPRITE 2, 0,0
			
			SETPIXEL gx, gy, pixel
			
			GRABSPRITE 2, 0,0, zwidth, zheight  // update black sprite

			SHOWSCREEN	
			
		NEXT

	NEXT
	
ENDFUNCTION

Sorry for my bad english :D

Title: Re: (My) stupid question (draw image pixel_by_pixel)
Post by: Kitty Hello on 2008-Jul-21

IF pixel > RGB(255,255,255)/2
You can't simply compare it this way.
Check, if the "green" component is bigger than 128:

IF bAND(pixel, 0x00ff00) > 0x008000 ...

Title: Re: (My) stupid question (draw image pixel_by_pixel)
Post by: PeeJay on 2008-Jul-22

If you need it deadly accurate, you will need to compare red, green, and blue components of course, which you could do like this:-

Code (glbasic) Select


pixel = GETPIXEL (x,y)
red = bAND(pixel,255)
green = bAND(pixel/256,255)
blue = bAND(pixel/65536,255)
mono = INTEGER(((red+green+blue)/3)/128)

Where mono would then by 0 for a black pixel, or 1 for a white pixel.

However, be aware that pixel by pixel operations are slow, since it is not really what the language was designed for ;)