I am using Imagick::resizeImage to create a thumbnail PNG image of each page of a pdf file. However, the image I am getting back is really blurry. How can I make it a little sharper? Any pointers would be really appreciated.
I have tried adjusting the 'blur' paramter of Imagick::resizeImage between 0.1 - 1, without success.
$pdfPage = '1Mpublic.pdf[0]';
$im = new imagick($pdfPage);
$im->setImageFormat('png');
// Resize thumbnail image
$imgHeight = $im -> getImageHeight();
$imgWidth = $im -> getImageWidth();
$desiredWidth = 200;
$desiredHeight = resizedImageHeight($imgWidth, $imgHeight, $desiredWidth);
$im -> setResolution(1500, 1500);
$im -> resizeImage($desiredWidth, $desiredHeight, imagick::STYLE_NORMAL, 0.1);
/* Resize image */
function resizedImageHeight($imgWidth, $imgHeight, $desiredImgWidth){
$quoient = $imgWidth/$imgHeight;
$height = $desiredImgWidth/$quoient;
return $height;
}
original pdf link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4905263/pdf/ksgt-06-04-1091539.pdf
Rather than rendering and then resizing the raster, it might be better to render the PDF to the right number of pixels in the first place. It'll be faster, and you can be sure that the amount of sharpness is correct for the content.
For example:
$ time convert -density 50 ksgt-06-04-1091539.pdf[0] x2.png
real 0m0.325s
user 0m0.299s
sys 0m0.024s
Makes:
The -density 50 makes a page about the same number of pixels across as your sample, 425.
In imagick you could do it like this (as #fmw42's excellent answer already says):
#!/usr/bin/env php
<?php
$target_width = 400;
# get natural size, calculate density we need for target width
$im = new imagick();
$im->pingImage($argv[1]);
$geo = $im->getImageGeometry();
$natural_width = $geo['width'];
$density = 72.0 * $target_width / $natural_width;
# load at correct resolution for target_width
$im = new imagick();
$im->setResolution($density, $density);
$im->readImage($argv[1]);
# and write back
$im->writeImage($argv[2]);
Doing both the ping and the read is a little slow in imagick, unfortunately:
$ time ./pdfthumb.php ksgt-06-04-1091539.pdf x.png
real 0m2.773s
user 0m2.737s
sys 0m0.036s
It's not imagick, but vipsthumbnail can do the ping and read in one operation:
$ time vipsthumbnail ksgt-06-04-1091539.pdf -s 400x -o x2.png
real 0m0.064s
user 0m0.064s
sys 0m0.011s
It might be worth considering if speed is important. libvips has a php binding so you can call it directly, but if you do that you'll run into awful licensing problems because it uses the GPL library poppler for PDF rendering, sigh. ImageMagick uses GhostScript and shells out to that for the same reason.
Unfortunately, I do not know Imagick that well. But in Imagemagick command line, I would do what is sometimes called supersampling. That is use a large density to read the PDF, then resize down by the inverse scale factor.
For example, nominal density is 72 dpi. I would read the input PDF at 4*72=288 dpi. Then after rasterizing, I would resize by 1/4=25% or for a larger result by something larger than 25%, say 50%. Here is your first page done both ways:
convert -density 288 ksgt-06-04-1091539.pdf[0] -resize 25% result1.png
convert -density 288 ksgt-06-04-1091539.pdf[0] -resize 50% result2.png
In Imagick, the key is something like:
$imagick = new Imagick();
$imagick->setImageResolution(288, 288);
$imagick->readImage('myfile.pdf');
I'm using PHP Imagick to convert PNG images generated in PhantomJS to TIF CMYK,
for print purposes I need a flat Black (cmyk - 0,0,0,100) - the conversion generates blacks like (cmyk - 58,49,44,89).
I'm converting the images using color profile (section of my code below) -> the code is based on Convert image from RGB to CMYK with Imagick
is it possible to force a flat black with Imagick ? do you know any other tools that might help ?
thanks,
if ($has_icc_profile === false) {
$icc_rgb = file_get_contents( '/srgb_profiles' . '/sRGB.icc');
$image->profileImage('icc', $icc_rgb);
unset($icc_rgb);
}
// then we add an CMYK profile
$icc_cmyk = file_get_contents( '/cmyk_profiles'.'/JapanColor2002Newspaper.icc');
$image->profileImage('icc', $icc_cmyk);
UPDATE :
after checking online I think I'm looking for a UCR en.wikipedia.org/wiki/Under_color_removal method for ImageMagick - I found that convert old versions supported under color removal
-undercolor <undercolor factor>x<black-generation factor>
control undercolor removal and black generation on CMYK images.
This option enables you to perform undercolor removal and black generation on CMYK images-- images to be printed on a four-color printing system. You can con- trol how much cyan, magenta, and yellow to remove from your image and how much black to add to it. The standard undercolor removal is 1.0x1.0. You'll frequently get better results, though, if the percentage of black you add to your image is slightly higher than the percentage of C, M, and Y you remove from it. For example you might try 0.5x0.7. (http://www.chemie.fu-berlin.de/chemnet/use/suppl/imagemagick/www/convert.html) -
apparently the option is not supported anymore, I'm interested if anyone knows if UCR is the solution I'm looking for and if anyone knows if it's supported or if I'm supposed to use a different method to get the same result.
If you use ImageMagick's convert at the command line like this to generate a grayscale ramp, 1 pixel wide and 256 pixels tall, going from white to black and convert it to CMYK colorspace and then show it as text, you get what you want:
convert -size 1x256 'gradient:rgb(255,255,255)-rgb(0,0,0)' -colorspace cmyk txt:
# ImageMagick pixel enumeration: 1,256,65535,cmyk
0,0: (0%,0%,0%,0%) #0000000000000000 cmyk(0,0,0,0)
0,1: (0%,0%,0%,0.392157%) #0000000000000101 cmyk(0,0,0,1)
0,2: (0%,0%,0%,0.784314%) #0000000000000202 cmyk(0,0,0,2)
0,3: (0%,0%,0%,1.17647%) #0000000000000303 cmyk(0,0,0,3)
0,4: (0%,0%,0%,1.56863%) #0000000000000404 cmyk(0,0,0,4)
0,5: (0%,0%,0%,1.96078%) #0000000000000505 cmyk(0,0,0,5)
0,6: (0%,0%,0%,2.35294%) #0000000000000606 cmyk(0,0,0,6)
0,7: (0%,0%,0%,2.7451%) #0000000000000707 cmyk(0,0,0,7)
0,8: (0%,0%,0%,3.13725%) #0000000000000808 cmyk(0,0,0,8)
0,9: (0%,0%,0%,3.52941%) #0000000000000909 cmyk(0,0,0,9)
0,10: (0%,0%,0%,3.92157%) #0000000000000A0A cmyk(0,0,0,10)
...
...
0,249: (0%,0%,0%,97.6471%) #000000000000F9F9 cmyk(0,0,0,249)
0,250: (0%,0%,0%,98.0392%) #000000000000FAFA cmyk(0,0,0,250)
0,251: (0%,0%,0%,98.4314%) #000000000000FBFB cmyk(0,0,0,251)
0,252: (0%,0%,0%,98.8235%) #000000000000FCFC cmyk(0,0,0,252)
0,253: (0%,0%,0%,99.2157%) #000000000000FDFD cmyk(0,0,0,253)
0,254: (0%,0%,0%,99.6078%) #000000000000FEFE cmyk(0,0,0,254)
0,255: (0%,0%,0%,100%) #000000000000FFFF cmyk(0,0,0,255)
You must be doing something different - maybe this will help you work it out. I am guessing it is your ICC profiles but you can experiment with the above command.
If you just want to experiment with spot values, you can just have IM translate a single pixel like this:
convert -size 1x1 xc:#000000 -colorspace cmyk txt:
# ImageMagick pixel enumeration: 1,1,65535,cmyk
0,0: (0%,0%,0%,100%) #000000000000FFFF cmyk(0,0,0,255)
or maybe more simply like this:
convert -size 1x1 xc:#000000 -depth 8 -colorspace cmyk txt:
# ImageMagick pixel enumeration: 1,1,255,cmyk
0,0: (0,0,0,255) #000000FF cmyk(0,0,0,255)
Note the following though:
You must put profiles between input image and output image names on the command line.
If your image has no embedded profile, the first profile you give is applied to the input image and the second to the output image. If your input image does have a profile, the first profile you give is applied to the output image.
I'm attempting to try and assign a value to an image based on its 'saturation level', to see if the image is black and white or color. I'm using Imagick, and have found what seems to be the perfect code for the command line and am trying to replicate it using the PHP library.
I think I understand the concept:
Convert image to HSL.
Extract the 'g' channel (which is the S channel in HSL).
Calculate the mean of this channel.
Command line code
convert '$image_path' -colorspace HSL -channel g -separate +channel -format '%[fx:mean]' info:
My PHP code
$imagick = new Imagick($image_path);
$imagick->setColorspace(imagick::COLORSPACE_HSL);
print_r($imagick->getImageChannelMean(imagick::CHANNEL_GREEN));
Output
My PHP code isn't outputting the same sort of values as the command line code, though. For example, a grayscale image gives 0 for the command line code, but the PHP code gives [mean] => 10845.392051182 [standardDeviation] => 7367.5888849872.
Similarly, another grayscale image gives 0 vs. [mean] => 31380.528443457 [standardDeviation] => 19703.501101904.
A colorful image gives 0.565309 vs. [mean] => 33991.552881892 [standardDeviation] => 16254.018540044.
There just doesn't seem to be any kind of pattern between the different values. Am I doing something obviously wrong?
Thanks.
Just to add, I've also tried this PHP code
$imagick = new Imagick($image_path);
$imagick->setColorspace(imagick::COLORSPACE_HSL);
$imagick->separateImageChannel(imagick::CHANNEL_GREEN);
$imagick->setFormat('%[fx:mean]');
But I get an Unable to set format error when I try and set the format. I've also tried setFormat('%[fx:mean] info:'), setFormat('%[mean]'), setFormat('%mean'), etc.
Update — FIXED!
Thanks to #danack for figuring out I needed to use transformImageColorspace() and not setColorspace(). The working code is below.
$imagick = new Imagick($image_path);
$imagick->transformImageColorspace(imagick::COLORSPACE_HSL);
$saturation_channel = $imagick->getImageChannelMean(imagick::CHANNEL_GREEN);
$saturation_level = $saturation_channel['mean']/65535;
setFormat doesn't replicate the command line option -format - the one in Imagick tries to set the image format, which should be png, jpg etc. The one in the command line is setting the format for info - the closest match for which in Imagick is calling $imagick->identifyImage(true) and parsing the results of that.
Also you're just calling the wrong function - it should be transformImageColorspace not setColorSpace. If you use that you can use the statistics from getImageChannelMean.
There are other ways to test for greyness which may be more appropriate under certain circumstances. The first is to convert the a clone of the image to grayscale, and then compare it to the original image:
$imagick = new Imagick($image_path);
$imagickGrey = clone $imagick;
$imagickGrey->setimagetype(\Imagick::IMGTYPE_GRAYSCALE);
$differenceInfo = $imagick->compareimages($imagickGrey, \Imagick::METRIC_MEANABSOLUTEERROR);
if ($differenceInfo['mean'] <= 0.0000001) {
echo "Grey enough";
}
That would probably be appropriate if you image had areas of color that were also transparent - so they theoretically have color, but not visibly.
Or if you only care about whether the image is of a grayscale format:
$imageType = $imagick->getImageType();
if ($imageType === \Imagick::IMGTYPE_GRAYSCALE ||
$imageType === Imagick::IMGTYPE_GRAYSCALEMATTE) {
//This is grayscale
}
I found a command line here:
convert image.png -colorspace HSL -channel g -separate +channel -format "%[fx:mean]" info:
It prints a number between 0 and 1, where zero means grayscale.
If your images have tint. (from scanner as example) you should do auto color for them before detecting gray scale.
You should normalizeImage(imagick::CHANNEL_ALL) for all separate channels of image. separateImageChannel()
But
I have a set of 10 jpegs.
I need to generate 1 SINGLE PDF of these 10 images using PDF.
(1 page = 1 jpeg)
Final result must be a PDF.
Can imagemagick php extension help me with that ?
Yes, it can. Sample code:
<?php
$files = array(realpath('t1.jpg'), realpath('t2.jpg'));
$image = new Imagick($files);
$image->setImageFormat('pdf');
$image->writeImages(__DIR__ . '/file.pdf', true);
The second parameter of Imagick::writeImages() controls if the resulting output is joined into one file.
Footnote: At least on windows, Imagick needs to be used with absolute paths.
convert -density 150 -size 1239x1754 xc:white -density 150 *test.jpg -gravity center -composite test.pdf
I'm trying to trim a variable amount of whitespace in an image only the left and right side using ImageMagick and PHP. Does anyone know how to do this (perhaps using something other than imagemagick?)?
Here's an example.
I have these two images:
Each has a variable amount of text that is dynamically created in a fixed width image.
What I need to do is trim the background off the right and left side so the images come out like this:
If ImageMagick can't do it, I am willing to use something else, but I will need help on how exactly because I am not much of a programmer. Thanks!
Here's my current code that trims all sides of an image:
<?php
/* Create the object and read the image in */
$i = '3';
$im = new Imagick("test".$i.".png");
/* Trim the image. */
$im->trimImage(0);
/* Ouput the image */
//header("Content-Type: image/" . $im->getImageFormat());
//echo $im;
/*** Write the trimmed image to disk ***/
$im->writeImage(dirname(__FILE__) . '/test'.$i.'.png');
/*Display Image*/
echo $img = "<img src=\"test".$i.".png\">";
?>
I think you are on the right track with ImageMagick's -trim operator 1), but the trick would be to get it tell you what it would do without actually doing it, and then modify that to do what you really want...
So, to get the trim-box ImageMagick calculates for your first image, you do this:
convert -fuzz 10% image.jpg -format "%#" info:
60x29+21+31
That is a 60x29 pixel rectangle, offset 21 across and 31 down from the top left corner. Now, we want to get these values into bash variables, so I set the IFS (Input Field Separator) to split fields on spaces, x and also + signs:
#!/bin/bash
IFS=" x+" read a b c d < <(convert -fuzz 10% image.jpg -format "%#" info:)
echo $a $b $c $d
60 29 21 31
Now I can ignore the 29 and the 31 because we are only interested in cropping the width, and crop like this:
convert image.jpg -crop "${a}x+${c}+0" out.jpg
So, for your 2 images, I get these:
and the full procedure is this:
#!/bin/bash
IFS=" x+" read a b c d < <(convert -fuzz 10% image.jpg -format "%#" info:)
convert image.jpg -crop "${a}x+${c}+0" out.jpg
Notes
1) The -format %# is just a shorthand for the -trim operator, which would be this in full
convert image.jpg -trim info:
image.jpg JPEG 72x40 200x100+16+24 8-bit sRGB 0.000u 0:00.000
From what I can see in the ImageMagick docs on cropping and borders, it doesn't seem to be possible.
you can't specify an edge for "intelligent" cropping (known as-trim on the command line), and all the cropping methods that accept a geometry argument need a fixed number for cropping.
The only idea that comes to mind is to get the colour of the shaved area in a separate call, run trimImage, and add the lost areas back using -border.
Edit: The IM manual is suggesting something similar. Check out Trimming Just One Side of an Image. I'm not familiar with IM's PHP extension to translate the code into PHP calls but it should be half-way straightforward.
The GD based library WideImage has something similar. It's called autoCrop, by default it works on all four sides.
However, you could just add another parameter and based on it only crop top/bottom or left/right.
autoCrop code
It's pretty well documented. $img is a WideImage_Image type. There is also an interactive online demo of it.
Related question: Removing black bars off video thumbnail.
Using GD:
function imageautocrop( &$img) {
$emptycol = function ( $img, $x, $min, $max) {
for( $y=$min; $y<$max; $y++) {
$col = imagecolorsforindex( $img, imagecolorat( $img, $x, $y));
if( $col['alpha'] != 127) return false;
}
return true;
}
$trim = Array('top'=>0,'bot'=>0,'lft'=>0,'rgt'=>0);
$size = Array('x'=>imagesx($img)-1,'y'=>imagesy($img)-1);
// code for affecting rows removed due to question asked
while( $emptycol( $img, $trim['lft'], $trim['top'], $size['y']-$trim['bot'])) $trim['lft']++;
while( $emptycol( $img, $size['x']-$trim['rgt'], $trim['top'], $size['y']-$trim['bot'])) $trim['rgt']++;
$newimg = imagecreate( $size['x']-$trim['lft']-$trim['rgt']+1, $size['y']-$trim['top']-$trim['bot']+1);
imagecopy( $newimg, $img, 0, 0, $trim['lft'], $trim['top'], imagesx($newimg)+1, imagesy($newimg)+1);
imagedestroy($img);
$img = $newimg;
}
It's very old code of mine, so probably not optimal, but it does the job.
It is a two step process as text is dynamically generated
Generate the text image, determine width(image)
Overlay text image into background, determine width(background)
Use one tool mentioned above, crop (width(background)-width(image)/2 on either side
The trick is figuring out the width(image). See: How can I auto adjust the width of a GD-generated image to fit the text?
Then again, if you know width(image), you can crop the width(background) first before overlay
Use cropImage() instead. Something like this, perhaps:
$img_x_size = 800; // Set these to relevant values
$img_y_size = 600;
$crop_pixels = 20; // How many pixels to crop
// cropImage(XsizeOfCrop, YsizeOfCrop, CropXPos, CropYPos)
$im->cropImage($img_x_size - $crop_pixels, $img_y_size, 0, $crop_pixels / 2);