Grayscaling Image with GD causes image to turn jet black!

**CountScubula** · Jul 17 '05, 02:55 AM

Re: Grayscaling Image with GD causes image to turn jet black!

Try running an average of the three colors:
$avg = floor( ( $color['red']) + $color['green']) + $color['blue']) ) / 3 )
$R= $avg; $B = $avg; $G = $avg;
imageColorSet($ image_id, $a, $R, $G, $B);

--
Mike Bradley
http://www.gzentools.com -- free online php tools
"Phil Powell" <soazine@erols. com> wrote in message
news:1cdca2a7.0 402030910.a9109 fc@posting.goog le.com...[color=blue]
> I borrowed this code from a source:
>
>
>
> for($a=0;$a<ima gecolorstotal ($image_id);$a+ +)
> {
> $color = imageColorsForI ndex($image_id, $i);
> $R=.299 * ($color['red'])+ .587 * ($color['green'])+ .114 *
> ($color['blue']);
> $G=.299 * ($color['red'])+ .587 * ($color['green'])+ .114 *
> ($color['blue']);
> $B=.299 * ($color['red'])+ .587 * ($color['green'])+ .114 *
> ($color['blue']);
> imageColorSet($ image_id, $a, $R, $G, $B);
> }
>
> using an image (in this case I'm using a JPEG) that is a true color
> image I was unable to successfully use imagecopymergeg ray since that
> washed out my hues/saturation altogether making the image illegible
> (imagecopymerge gray + imagecreate); otherwise, the colors overrode
> imagecopymergeg ray (imagecopymerge gray + imagecreatetrue color).
>
> Using the code I borrowed I was able to change the image.. except that
> it turned jet black instead!
>
> Has anyone ever successfully grayscaled an image using GD library? If
> so, how did you do it?
>
> Thanx
> Phil[/color]

**Phil Powell** · Jul 17 '05, 02:56 AM

Re: Grayscaling Image with GD causes image to turn jet black!

I'm sorry but that too breaks. Perhaps a code review is in order, I
realize that imageColorsTota l($this->image) produces 0, which I am
afraid I don't understand:

class ImageGrayscaleG enerator {

/*---------------------------------------------------------------------------------------------------------------------------------------------------------
This class exists due to the rather poor performance of the
imagecopymergeg ray() command
Borrowing code snippet from
http://us3.php.net/manual/en/functio...ymergegray.php first
line comment
Will perform actual grayscaling of image one pixel at a time.
-----------------------------------------------------------------------------------------------------------------------------------------------------------*/

var $image, $image_width, $image_height;

// REMEMBER TO USE REFERENCE POINTER ONTO $image OBJECT TO ENSURE
"static" CHANGE TO OBJECT AND NOT TO INSTANCE

function ImageGrayscaleG enerator(&$imag e) { // CONSTRUCTOR
$this->image =& $image;
}

function makeGray() { // VOID METHOD
print_r($this->image); print_r("");
print_r(@imageC olorsTotal($thi s->image) . "");
for ($i = 0; $i < @imagecolorstot al($this->image); $i++) {
$colorArray = @imageColorsFor Index($this->image, $i);
print_r($colorA rray); print_r("");
$avg = floor(($colorAr ray['red'] + $colorArray['green'] +
$colorArray['blue']) / 3);
@imageColorSet( $this->image, $i, $avg, $avg, $avg);
}
}
}

Thanx
Phil

"CountScubu la" <me@scantek.hot mail.com> wrote in message news:<_rSTb.197 24$up5.18401@ne wssvr27.news.pr odigy.com>...[color=blue]
> Try running an average of the three colors:
> $avg = floor( ( $color['red']) + $color['green']) + $color['blue']) ) / 3 )
> $R= $avg; $B = $avg; $G = $avg;
> imageColorSet($ image_id, $a, $R, $G, $B);
>
>
> --
> Mike Bradley
> http://www.gzentools.com -- free online php tools
> "Phil Powell" <soazine@erols. com> wrote in message
> news:1cdca2a7.0 402030910.a9109 fc@posting.goog le.com...[color=green]
> > I borrowed this code from a source:
> >
> >
> >
> > for($a=0;$a<ima gecolorstotal ($image_id);$a+ +)
> > {
> > $color = imageColorsForI ndex($image_id, $i);
> > $R=.299 * ($color['red'])+ .587 * ($color['green'])+ .114 *
> > ($color['blue']);
> > $G=.299 * ($color['red'])+ .587 * ($color['green'])+ .114 *
> > ($color['blue']);
> > $B=.299 * ($color['red'])+ .587 * ($color['green'])+ .114 *
> > ($color['blue']);
> > imageColorSet($ image_id, $a, $R, $G, $B);
> > }
> >
> > using an image (in this case I'm using a JPEG) that is a true color
> > image I was unable to successfully use imagecopymergeg ray since that
> > washed out my hues/saturation altogether making the image illegible
> > (imagecopymerge gray + imagecreate); otherwise, the colors overrode
> > imagecopymergeg ray (imagecopymerge gray + imagecreatetrue color).
> >
> > Using the code I borrowed I was able to change the image.. except that
> > it turned jet black instead!
> >
> > Has anyone ever successfully grayscaled an image using GD library? If
> > so, how did you do it?
> >
> > Thanx
> > Phil[/color][/color]

**CountScubula** · Jul 17 '05, 02:57 AM

Re: Grayscaling Image with GD causes image to turn jet black!

sorry, I didnt really look at the code, how is it breaking, error, not
working?

--
Mike Bradley
http://www.gzentools.com -- free online php tools
"Phil Powell" <soazine@erols. com> wrote in message
news:1cdca2a7.0 402040711.63478 c64@posting.goo gle.com...[color=blue]
> I'm sorry but that too breaks. Perhaps a code review is in order, I
> realize that imageColorsTota l($this->image) produces 0, which I am
> afraid I don't understand:
>
> class ImageGrayscaleG enerator {
>
>[/color]
/*--------------------------------------------------------------------------
----------------------------------------------------------------------------
---[color=blue]
> This class exists due to the rather poor performance of the
> imagecopymergeg ray() command
> Borrowing code snippet from
> http://us3.php.net/manual/en/functio...ymergegray.php first
> line comment
> Will perform actual grayscaling of image one pixel at a time.
> --------------------------------------------------------------------------[/color]
----------------------------------------------------------------------------
-----*/[color=blue]
>
> var $image, $image_width, $image_height;
>
> // REMEMBER TO USE REFERENCE POINTER ONTO $image OBJECT TO ENSURE
> "static" CHANGE TO OBJECT AND NOT TO INSTANCE
>
> function ImageGrayscaleG enerator(&$imag e) { // CONSTRUCTOR
> $this->image =& $image;
> }
>
> function makeGray() { // VOID METHOD
> print_r($this->image); print_r("");
> print_r(@imageC olorsTotal($thi s->image) . "");
> for ($i = 0; $i < @imagecolorstot al($this->image); $i++) {
> $colorArray = @imageColorsFor Index($this->image, $i);
> print_r($colorA rray); print_r("");
> $avg = floor(($colorAr ray['red'] + $colorArray['green'] +
> $colorArray['blue']) / 3);
> @imageColorSet( $this->image, $i, $avg, $avg, $avg);
> }
> }
> }
>
>
> Thanx
> Phil
>
> "CountScubu la" <me@scantek.hot mail.com> wrote in message[/color]
news:<_rSTb.197 24$up5.18401@ne wssvr27.news.pr odigy.com>...[color=blue][color=green]
> > Try running an average of the three colors:
> > $avg = floor( ( $color['red']) + $color['green']) + $color['blue']) ) /[/color][/color]
3 )[color=blue][color=green]
> > $R= $avg; $B = $avg; $G = $avg;
> > imageColorSet($ image_id, $a, $R, $G, $B);
> >
> >
> > --
> > Mike Bradley
> > http://www.gzentools.com -- free online php tools
> > "Phil Powell" <soazine@erols. com> wrote in message
> > news:1cdca2a7.0 402030910.a9109 fc@posting.goog le.com...[color=darkred]
> > > I borrowed this code from a source:
> > >
> > >
> > >
> > > for($a=0;$a<ima gecolorstotal ($image_id);$a+ +)
> > > {
> > > $color = imageColorsForI ndex($image_id, $i);
> > > $R=.299 * ($color['red'])+ .587 * ($color['green'])+ .114 *
> > > ($color['blue']);
> > > $G=.299 * ($color['red'])+ .587 * ($color['green'])+ .114 *
> > > ($color['blue']);
> > > $B=.299 * ($color['red'])+ .587 * ($color['green'])+ .114 *
> > > ($color['blue']);
> > > imageColorSet($ image_id, $a, $R, $G, $B);
> > > }
> > >
> > > using an image (in this case I'm using a JPEG) that is a true color
> > > image I was unable to successfully use imagecopymergeg ray since that
> > > washed out my hues/saturation altogether making the image illegible
> > > (imagecopymerge gray + imagecreate); otherwise, the colors overrode
> > > imagecopymergeg ray (imagecopymerge gray + imagecreatetrue color).
> > >
> > > Using the code I borrowed I was able to change the image.. except that
> > > it turned jet black instead!
> > >
> > > Has anyone ever successfully grayscaled an image using GD library? If
> > > so, how did you do it?
> > >
> > > Thanx
> > > Phil[/color][/color][/color]

**Phil Powell** · Jul 17 '05, 02:57 AM

Re: Grayscaling Image with GD causes image to turn jet black!

"CountScubu la" <me@scantek.hot mail.com> wrote in message news:<bEdUb.202 02$CX7.1043@new ssvr27.news.pro digy.com>...[color=blue]
> sorry, I didnt really look at the code, how is it breaking, error, not
> working?[/color]

I'll show you, just go down and view...

Phil
[color=blue]
>
> --
> Mike Bradley
> http://www.gzentools.com -- free online php tools
> "Phil Powell" <soazine@erols. com> wrote in message
> news:1cdca2a7.0 402040711.63478 c64@posting.goo gle.com...[color=green]
> > I'm sorry but that too breaks. Perhaps a code review is in order, I
> > realize that imageColorsTota l($this->image) produces 0, which I am
> > afraid I don't understand:
> >
> > class ImageGrayscaleG enerator {
> >
> >[/color]
> /*--------------------------------------------------------------------------
> ----------------------------------------------------------------------------
> ---[color=green]
> > This class exists due to the rather poor performance of the
> > imagecopymergeg ray() command
> > Borrowing code snippet from
> > http://us3.php.net/manual/en/functio...ymergegray.php first
> > line comment
> > Will perform actual grayscaling of image one pixel at a time.
> > --------------------------------------------------------------------------[/color]
> ----------------------------------------------------------------------------
> -----*/[color=green]
> >
> > var $image, $image_width, $image_height;
> >
> > // REMEMBER TO USE REFERENCE POINTER ONTO $image OBJECT TO ENSURE
> > "static" CHANGE TO OBJECT AND NOT TO INSTANCE
> >
> > function ImageGrayscaleG enerator(&$imag e) { // CONSTRUCTOR
> > $this->image =& $image;
> > }
> >
> > function makeGray() { // VOID METHOD
> > print_r($this->image); print_r("");
> > print_r(@imageC olorsTotal($thi s->image) . "");[/color][/color]

** STOP HERE! What happens is that imageColorsTota l($this->image) =
0! Though the image is in color and I do a reference pointer to the
$image resource paramters in the method call, and it actually DOES
change the image according to the value of
imageColorsTota l($this->image), it turns the entire image into one
jet-black image, no tone, no hue, nothing, a big black box.

Phil
[color=blue][color=green]
> > for ($i = 0; $i < @imagecolorstot al($this->image); $i++) {
> > $colorArray = @imageColorsFor Index($this->image, $i);
> > print_r($colorA rray); print_r("");
> > $avg = floor(($colorAr ray['red'] + $colorArray['green'] +
> > $colorArray['blue']) / 3);
> > @imageColorSet( $this->image, $i, $avg, $avg, $avg);
> > }
> > }
> > }
> >
> >
> > Thanx
> > Phil
> >
> > "CountScubu la" <me@scantek.hot mail.com> wrote in message[/color]
> news:<_rSTb.197 24$up5.18401@ne wssvr27.news.pr odigy.com>...[color=green][color=darkred]
> > > Try running an average of the three colors:
> > > $avg = floor( ( $color['red']) + $color['green']) + $color['blue']) ) /[/color][/color]
> 3 )[color=green][color=darkred]
> > > $R= $avg; $B = $avg; $G = $avg;
> > > imageColorSet($ image_id, $a, $R, $G, $B);
> > >
> > >
> > > --
> > > Mike Bradley
> > > http://www.gzentools.com -- free online php tools
> > > "Phil Powell" <soazine@erols. com> wrote in message
> > > news:1cdca2a7.0 402030910.a9109 fc@posting.goog le.com...
> > > > I borrowed this code from a source:
> > > >
> > > >
> > > >
> > > > for($a=0;$a<ima gecolorstotal ($image_id);$a+ +)
> > > > {
> > > > $color = imageColorsForI ndex($image_id, $i);
> > > > $R=.299 * ($color['red'])+ .587 * ($color['green'])+ .114 *
> > > > ($color['blue']);
> > > > $G=.299 * ($color['red'])+ .587 * ($color['green'])+ .114 *
> > > > ($color['blue']);
> > > > $B=.299 * ($color['red'])+ .587 * ($color['green'])+ .114 *
> > > > ($color['blue']);
> > > > imageColorSet($ image_id, $a, $R, $G, $B);
> > > > }
> > > >
> > > > using an image (in this case I'm using a JPEG) that is a true color
> > > > image I was unable to successfully use imagecopymergeg ray since that
> > > > washed out my hues/saturation altogether making the image illegible
> > > > (imagecopymerge gray + imagecreate); otherwise, the colors overrode
> > > > imagecopymergeg ray (imagecopymerge gray + imagecreatetrue color).
> > > >
> > > > Using the code I borrowed I was able to change the image.. except that
> > > > it turned jet black instead!
> > > >
> > > > Has anyone ever successfully grayscaled an image using GD library? If
> > > > so, how did you do it?
> > > >
> > > > Thanx
> > > > Phil[/color][/color][/color]

**CountScubula** · Jul 17 '05, 02:57 AM

Re: Grayscaling Image with GD causes image to turn jet black!

"Phil Powell" <soazine@erols. com> wrote in message
news:1cdca2a7.0 402042019.1ed5f cce@posting.goo gle.com...[color=blue]
>
> I'll show you, just go down and view...
>
> Phil
>
> < Big-O-snip >[/color]

Sometimes easier to re-invent the wheel (thats my my cars don't have model-t
wheels on them)
here is some code that works, and you can test here:

http://www.gzentools.com/test/img2gry.php

<?php

$imgFile = "girl1.jpg" ;

$imSrc = imagecreatefrom jpeg($imgFile);

$imW = imagesx($imSrc) ;
$imH = imagesy($imSrc) ;

$imDst = imagecreate($im W,$imH);

// create 256 shades of grey
for ($i=0; $i<256; $i++) {
$colorNdx[$i] = imagecoloralloc ate($imDst,$i,$ i,$i);
}

for ($y=0; $y<$imH; $y++)
{
for ($x=0; $x<$imW; $x++)
{
$ndx = imagecolorat($i mSrc,$x,$y);
$ndxColors = imagecolorsfori ndex($imSrc,$nd x);
$avg = floor( ($ndxColors['red'] + $ndxColors['green'] +
$ndxColors['blue']) / 3 );
imagesetpixel($ imDst,$x,$y,$co lorNdx[$avg]);
}
}

imagejpeg($imDs t);
exit();

?>

--
Mike Bradley
http://www.gzentools.com -- free online php tools

**Phil Powell** · Jul 17 '05, 02:58 AM

Re: Grayscaling Image with GD causes image to turn jet black!

IT WORKED AT LAST!!! Thanx a lot. By the way, your URL produced
ASCII-related garbage on my screen, just so you know.

Thanx again!!
Phil

"CountScubu la" <me@scantek.hot mail.com> wrote in message news:<vikUb.203 69$ja5.12921@ne wssvr27.news.pr odigy.com>...[color=blue]
> "Phil Powell" <soazine@erols. com> wrote in message
> news:1cdca2a7.0 402042019.1ed5f cce@posting.goo gle.com...[color=green]
> >
> > I'll show you, just go down and view...
> >
> > Phil
> >
> > < Big-O-snip >[/color]
>
> Sometimes easier to re-invent the wheel (thats my my cars don't have model-t
> wheels on them)
> here is some code that works, and you can test here:
> http://www.gzentools.com/test/img2gry.php
>
>
>
> <?php
>
> $imgFile = "girl1.jpg" ;
>
> $imSrc = imagecreatefrom jpeg($imgFile);
>
> $imW = imagesx($imSrc) ;
> $imH = imagesy($imSrc) ;
>
> $imDst = imagecreate($im W,$imH);
>
> // create 256 shades of grey
> for ($i=0; $i<256; $i++) {
> $colorNdx[$i] = imagecoloralloc ate($imDst,$i,$ i,$i);
> }
>
> for ($y=0; $y<$imH; $y++)
> {
> for ($x=0; $x<$imW; $x++)
> {
> $ndx = imagecolorat($i mSrc,$x,$y);
> $ndxColors = imagecolorsfori ndex($imSrc,$nd x);
> $avg = floor( ($ndxColors['red'] + $ndxColors['green'] +
> $ndxColors['blue']) / 3 );
> imagesetpixel($ imDst,$x,$y,$co lorNdx[$avg]);
> }
> }
>
> imagejpeg($imDs t);
> exit();
>
> ?>[/color]

**CountScubula** · Jul 17 '05, 02:58 AM

Re: Grayscaling Image with GD causes image to turn jet black!

Like like I forgot to inflate the tire after I reinvented the wheel, forgot
to put:
header("Content-type: image/jpeg");

--
Mike Bradley
http://www.gzentools.com -- free online php tools
"Phil Powell" <soazine@erols. com> wrote in message
news:1cdca2a7.0 402051025.2dc18 05b@posting.goo gle.com...[color=blue]
> IT WORKED AT LAST!!! Thanx a lot. By the way, your URL produced
> ASCII-related garbage on my screen, just so you know.
>
> Thanx again!!
> Phil
>
> "CountScubu la" <me@scantek.hot mail.com> wrote in message[/color]
news:<vikUb.203 69$ja5.12921@ne wssvr27.news.pr odigy.com>...[color=blue][color=green]
> > "Phil Powell" <soazine@erols. com> wrote in message
> > news:1cdca2a7.0 402042019.1ed5f cce@posting.goo gle.com...[color=darkred]
> > >
> > > I'll show you, just go down and view...
> > >
> > > Phil
> > >
> > > < Big-O-snip >[/color]
> >
> > Sometimes easier to re-invent the wheel (thats my my cars don't have[/color][/color]
model-t[color=blue][color=green]
> > wheels on them)
> > here is some code that works, and you can test here:
> > http://www.gzentools.com/test/img2gry.php
> >
> >
> >
> > <?php
> >
> > $imgFile = "girl1.jpg" ;
> >
> > $imSrc = imagecreatefrom jpeg($imgFile);
> >
> > $imW = imagesx($imSrc) ;
> > $imH = imagesy($imSrc) ;
> >
> > $imDst = imagecreate($im W,$imH);
> >
> > // create 256 shades of grey
> > for ($i=0; $i<256; $i++) {
> > $colorNdx[$i] = imagecoloralloc ate($imDst,$i,$ i,$i);
> > }
> >
> > for ($y=0; $y<$imH; $y++)
> > {
> > for ($x=0; $x<$imW; $x++)
> > {
> > $ndx = imagecolorat($i mSrc,$x,$y);
> > $ndxColors = imagecolorsfori ndex($imSrc,$nd x);
> > $avg = floor( ($ndxColors['red'] + $ndxColors['green'] +
> > $ndxColors['blue']) / 3 );
> > imagesetpixel($ imDst,$x,$y,$co lorNdx[$avg]);
> > }
> > }
> >
> > imagejpeg($imDs t);
> > exit();
> >
> > ?>[/color][/color]

**Phil Powell** · Jul 17 '05, 02:59 AM

Re: Grayscaling Image with GD causes image to turn jet black!

Sorry I can't add that header() line, the moment I do, "index.php"
turns literally into an indiscernible JPEG image (that's assuming I'm
working with a JPEG, in my Image Catalog it could literally be
anything, even a video!)

Phil

"CountScubu la" <me@scantek.hot mail.com> wrote in message news:<VPwUb.983 0$G95.7608@news svr29.news.prod igy.com>...[color=blue]
> Like like I forgot to inflate the tire after I reinvented the wheel, forgot
> to put:
> header("Content-type: image/jpeg");
>
> --
> Mike Bradley
> http://www.gzentools.com -- free online php tools
> "Phil Powell" <soazine@erols. com> wrote in message
> news:1cdca2a7.0 402051025.2dc18 05b@posting.goo gle.com...[color=green]
> > IT WORKED AT LAST!!! Thanx a lot. By the way, your URL produced
> > ASCII-related garbage on my screen, just so you know.
> >
> > Thanx again!!
> > Phil
> >
> > "CountScubu la" <me@scantek.hot mail.com> wrote in message[/color]
> news:<vikUb.203 69$ja5.12921@ne wssvr27.news.pr odigy.com>...[color=green][color=darkred]
> > > "Phil Powell" <soazine@erols. com> wrote in message
> > > news:1cdca2a7.0 402042019.1ed5f cce@posting.goo gle.com...
> > > >
> > > > I'll show you, just go down and view...
> > > >
> > > > Phil
> > > >
> > > > < Big-O-snip >
> > >
> > > Sometimes easier to re-invent the wheel (thats my my cars don't have[/color][/color]
> model-t[color=green][color=darkred]
> > > wheels on them)
> > > here is some code that works, and you can test here:
> > > http://www.gzentools.com/test/img2gry.php
> > >
> > >
> > >
> > > <?php
> > >
> > > $imgFile = "girl1.jpg" ;
> > >
> > > $imSrc = imagecreatefrom jpeg($imgFile);
> > >
> > > $imW = imagesx($imSrc) ;
> > > $imH = imagesy($imSrc) ;
> > >
> > > $imDst = imagecreate($im W,$imH);
> > >
> > > // create 256 shades of grey
> > > for ($i=0; $i<256; $i++) {
> > > $colorNdx[$i] = imagecoloralloc ate($imDst,$i,$ i,$i);
> > > }
> > >
> > > for ($y=0; $y<$imH; $y++)
> > > {
> > > for ($x=0; $x<$imW; $x++)
> > > {
> > > $ndx = imagecolorat($i mSrc,$x,$y);
> > > $ndxColors = imagecolorsfori ndex($imSrc,$nd x);
> > > $avg = floor( ($ndxColors['red'] + $ndxColors['green'] +
> > > $ndxColors['blue']) / 3 );
> > > imagesetpixel($ imDst,$x,$y,$co lorNdx[$avg]);
> > > }
> > > }
> > >
> > > imagejpeg($imDs t);
> > > exit();
> > >
> > > ?>[/color][/color][/color]

Grayscaling Image with GD causes image to turn jet black!

Grayscaling Image with GD causes image to turn jet black!

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