I want the new height and width to which the image needs to be resized. There are two conditions
Width needs to be around 180px(170-180) but < 180px (uploaded image is always > 180)
Height should be max 180px (uploaded image may or may not be > 180)
If you are writing program for Linux I would recommend using ImageMagick. It is more memory efficient and probably faster than any PHP based method. Almost all servers have it installed. Following code will do the trick.
function resizeTo($source, $dest, $w=180, $h=180) {
system("convert $source -resize {$w}x{$h} $dest");
}
It will mind the aspect ratio.
Edit:
Sorry for the confusion. I think the following should do what you are looking for. It is not tested and might need a little bit debugging, if you run into trouble I can try and post again.
//accepts and returns point object (having ->x and ->y)
function resizeTo($current, $max) {
if($current->x <= $max->x && $current->y <= $max->y) //you will not need this but
return $current; // still its good to have
if( ($current->y / $max->y) > ($current->x / $max->x) ) { //y axis needs more trimming
$r=$current->y / $max->y;
$current->y = $max->y;
$current->x = $current->x / $r;
} else {
$r=$current->x / $max->x;
$current->x = $max->x;
$current->y = $current->y / $r;
}
return $current;
}
You just need a few steps:
1. scale = imageWidth / 180;
2. scale = (imageHeight/scale>180) ? imageHeight/180 : scale;
The first one will set the scale factor you need to make the width 180 (based on your comment that it is ALWAYS larger then 180)
The second one will check if the height will be larger then 180 with that scale. If it is, then the scale will be height/180. If its not, you already have the max height.
Then you also need steps to get the actual width and height:
width = imageWidth/scale;
height = imageHeight/scale;
Considering you want to make the imageWidth between 170 and 180 I guess cropping the image is also a possibility. If that is the case you need an additional check
if (width<170) {
width = 170;
height = imageHeigh / (imageWidth/170);
//resize image to width and height
//crop image to height = 180
}
Related
Hey all i am trying to figure out how to resize an image that has a higher height than width. The normal width and height of the area where the image needs to be displayed is:
width = 1000px
height = 700px
What type of math would i need in order to resize that to the proper width/height above without screwing it?
The test image size is:
width = 1451
height = 2200
I was thinking of doing this:
(700/org.height)
But that does not come up with the correct number of 462.
In photoshop, changing the height to 700 yields a width value of 462.
so you want to scale your image so that it fits as large as possible within a 1000x700 square without stretching it? You could do something like this:
$availH = 700;
$availW = 1000;
$imageH = 2200;
$imageW = 1451;
// you know you want to limit the height to 700
$newH = $availH;
// figure out what the ratio was that you adjusted (will equal aprox 0.3181)
$ratio = $availH / $imageH;
// now that you have the $ratio you can apply that to the width (will equal 462)
$newW = round(imageW * $ratio);
Now you have $newW and $newH which are the new sizes for your image properly scaled. You could of course condense this down but I've written it out so each step is more clear.
Formula to keep aspect ratio when resizing is
original height / original width x new width = new height
Source: http://andrew.hedges.name/experiments/aspect_ratio/
But you want to switch it around to the following I think:
original width / original height x new height = new width
I just want to know if it is possible to get different images' sizes, and create fixed thumbnail dimension measurements for these pictures without losing their accurate aspect ratios.
So far, I have made these:
Resize different images
Maintain their aspect ratios
NOT supplying the same size (for example: 100px- height and 100px- width)
Here's the code that I am working with:
<?php
require("dbinfo.php");
$allPhotosQuery = mysql_query (" SELECT * FROM `placesImages` ");
while ($allPhotosArray = mysql_fetch_assoc ($allPhotosQuery))
{
$filename= $allPhotosArray['fileName'];
$placeId = $allPhotosArray['placeId'];
$imagePath = "placesImages/" . $placeId . "/" . $filename;
$imageSize = getimagesize($imagePath);
$imageWidth = $imageSize[0];
$imageHeight = $imageSize[1];
$newSize = ($imageWidth + $imageHeight)/($imageWidth*($imageHeight/45));
$newHeight = $imageHeight * $newSize;
$newWidth = $imageWidth * $newSize;
echo "<img src='".$imagePath."' width='".$newWidth."' height='".$newHeight."' />";
}
?>
Short of cropping, the simplest way to maintain aspect ratio while making a thumbnail is to do something similar to what you have, but set one fixed:
For example, if you want all your tumbs to be 100px wide:
$imageWidth = $imageSize[0];
$imageHeight = $imageSize[1];
$ratio=ImageWidth/$imageHeight;
$newHeight=(int)$ratio*100;
$newWidth=100;
The caveat with this is that you might end up with some funny sizes if the image has a funny ratio - as in it will happily go ahead and just do it. It might be a good idea to put some sort of check on the ratio in your code - if it it too low or too high, do something else, otherwise use this standard process.
feed this function your original image width and heights followed by the maximum constraints of your thumbnail limits and it will spit out an array with x/y of what you should set your thumbnail at to maintain aspect ratio. (anything smaller than the thumbnail will be enlarged)
function imageResizeDimensions($source_width,$source_height,$thumb_width,$thumb_height)
{
$source_ratio = $source_width / $source_height;
$thumb_ratio = $thumb_width / $thumb_height;
if($thumb_ratio > $source_ratio)
{
return array('x'=>$thumb_height * $source_ratio,'y'=>$thumb_height);
}
elseif($thumb_ratio < $source_ratio)
{
return array('x'=>$thumb_width,'y'=>$thumb_width/$source_ratio);
}
else
{
return array('x'=>$thumb_width,'y'=>$thumb_width);
}
}
Let’s begin with two constants, thumb_width and thumb_height, which are the desired width and height of your thumbnail images. They can be equal, but don’t have to be.
If you have an image that’s wider than it is tall (landscape) we can set the width to the desired width of the thumbnail, thumb_width, and adjust the height to maintain the aspect ratio.
new_width = thumb_width
new_height = thumb_height * old_height / old_width
See imagecreatetruecolor.
Then you can move the image to center it vertically within the limits of the thumbnail, producing a letterbox effect. See imagecopyresampled.
new_y = (thumb_height - new_height) / 2
For images that are taller than they are wide (portrait) the procedure is the same, but the math is a little different.
new_height = thumb_height
new_width = thumb_width * old_width / old_height
Then you can center it horizontally within the limits of the thumbnail.
new_x = (thumb_width - new_width) / 2
For more information on the basics of creating thumbnail images see Resizing images in PHP with GD and Imagick
I would like manipulate/resize images in a similar way to Pinterest but I am not sure what is the best way to approach it. The goal is to allow a mix of both portrait and landscape images but put some restrictions on the maximum height and width.
The problem i can see is that if I resize to a width, a portrait image may become too thin, and the opposite it true for a landscape image.
Any ideas on how to achieve those sort of results with PHP?
You just need to understand which of the two edges of the image is longer, and compute the other dimension proportionally. If the maximum long-egde is 1024, then if one of the two edges is larger you will set that to 1024, and compute the other to fit the proportions. Then you will pass those two values to your image management functions.
Like here:
http://www.white-hat-web-design.co.uk/blog/resizing-images-with-php/
Or here:
http://www.9lessons.info/2009/03/upload-and-resize-image-with-php.html
try with this
$needheight = 1000;
$needwidth = 1000;
$arrtest = getimagesize($upload_image_physical_path);
$actualwidth = $arrtest[0];
$actualheight = $arrtest[1];
if($needwidth > $actualwidth || $needheight > $actualheight){
//uplaod code
}
cheers
Check for a max size and then resize based on a ratio. Here's a pseudo code example:
if($imageHeight > $maxHeight) {
$newHeight = $maxHeight;
$newWidth = $imageWidth * ($maxHeight / $imageHeight);
}
if($imageWidth > $maxWidth) {
$newWidth = $maxWidth;
$newHeight = $imageHeight * ($maxWidth / $imageWidth);
}
resize($image, $newWidth, $newHeight);
It first checks the height and if the height is greater, it scales it down. Then it checks the width. If the width is too big, it scales it down again. The end result, both height and width will be with in your bounds. It uses the ratio to do the scaling.
Note, this is pseudocodish. The actual resize function call will depend on your image manipulation library -- same goes for calls to obtain image size.
I'm trying to generate thumbnails of the images my users upload. I have got the basic functionality to work by having my thumbnail class generate a thumbnail that is 50% of the width and height of the original image. However, I'd like to extend its functionality and enforce a hard limit on thumbnails that will be larger than 400px on either side after the 50% reduction.
This is what I have so far:
$x = $image_info[0]; // width of original image
$y = $image_info[1]; // height of original image
$x_t = $x/2; // width of 50% thumbnail
$y_t = $y/2; // height of 50% thumbnail
$biggest = ($x_t > $y_t) ? $x_t : $y_t; // determine the biggest side of the thumbnail
if($biggest > 400)
{
// Enforce a 400px limit here
/// somehow :(
}
With this hard limit, I want the original image to be scaled down so that no side exceeds 400px, and I want the other side to be scaled down relative so the image doesn't look distorted.
Being as terrible with math as I am, I can't work out a way to calculate the image dimensions that my thumbnail class should resize the image to.
Any ideas?
You'd have to compute a scaling factor:
$factor = $biggest / 400; // if 503, then factor = 1.2575;
$new_x = $x / $factor;
$new_y = $y / $factor;
and use those two new dimensions for your scaling. That'll reduce whatever side is $biggest to 400, and proportionally reduce the other dimension to something less than 400.
You will have to check for each length, not both at once:
if ($x > 400) {
$x_t = 400;
$y_t = $y * (400 / $x);
}
if ($y > 400) {
...
If $x is 600 for example, the calucalation would become $y_t = $y * (400 / 600), thus reducing $y to 2/3 of its original value.
And add the same condition for the $y side. Additionally you might want to apply the calculations concurrently, if neither side is allowed to be larger than 400.
How would I be able to detect that an image is blank (only of a single, arbitrary color or, with a gif, frames of random arbitrary colors) using PHP and/or imagemagick?
I think this is what I'm going to try:
http://www.php.net/manual/en/function.imagecolorat.php#97957
You can check the image inside of PHP using imagecolorat (this may be slow, but it works):
function isPngValidButBlank($filename) {
$img = imagecreatefrompng($filename);
if(!$img)
return false;
$width = imagesx($img);
$height = imagesy($img);
if(!$width || !$height)
return false;
$firstcolor = imagecolorat($img, 0, 0);
for($i = 0; $i < $width; $i++) {
for($j = 0; $j < $height; $j++) {
$color = imagecolorat($img, $i, $j);
if($color != $firstcolor)
return false;
}
}
return true;
}
http://www.php.net/manual/en/function.imagecolorstotal.php gives you the amount of colors in an image. Hmm, in my demo it doesn't seem to work, sorry :( an image i created (fully red, 20x20 pixels) gives 0 colors for PNG and 3 colors for GIF.
Ok: http://www.dynamicdrive.com/forums/showpost.php?p=161187&postcount=2 look at the 2nd piece of code. Tested here: http://www.pendemo.nl/totalcolors.php
Kevin's solution can be sped up using random sampling. If you have some idea of the percentage of pixels that should be different from the background (assuming you aren't dealing with lots of images with only 1 different pixel), you can use the Poisson distribution:
probability of finding a nonblank pixel = 1 - e^(-n*p)
where n is the number of samples to try, and p is the percentage of pixels expected to be nonblank. Solve for n to get the appropriate number of samples to try:
n = -log(1 - x) / p
where x is the desired probability and log is natural log. For example, if you are reasonably sure that 0.1% of the image should be nonblank, and you want to have a 99.99% chance of finding at least one nonblank pixel,
n = -log(1-.9999)/.001 = 9210 samples needed.
Much faster than checking every pixel. To be 100% sure, you can always go back and check all of them if the sampling doesn't find any.
For anyone using Imagick to try and achieve this, the getImageColors() method did the trick.
https://www.php.net/manual/en/imagick.getimagecolors.php
$img = new Imagick();
$img->readImage($image);
$colors = $img->getImageColors();
if(!$colors > 1) {
return false;
}
Get the standard-deviation from the verbose statistics for each tile. If the standard deviation is 0, then the image is one color.
Supposedly, 'number of colors' will also do this; would be 1.
Use the -format option: http://www.imagemagick.org/script/escape.php