Blurry uniform squared thumbnails

[Jan Klerks]

For my project I like to use uniform squared thumbnails. To do so I have set the uniform thumbnail feature to yes with both the Uniform thumbnail height and width set to 164 pixels. The issue is that Photopost makes okay thumbnails from vertical orientated images, but the thumbnails cropped from horizontal images are very blurry. You can see an example here. The first one (Legacy) is based on a horizontal image, the second one (2215) on a vertical one. Anyone knows what causes this and how to solve it?

[Chuck S]

What happens if you use the default Image sizes in the uniform thumbnails of 120x78? Are they okay.

Its a feature only available to imagemagick and I believe the formats must be like 120x78 or something similar like 180x156

[Jan Klerks]

120 (width) x 78 (height) looks fine, the other way around looks very blurry. (see here. But I'm not interested in 120 x 78. Plogger has the a feature to use squared cropped images and these thumbnails come out nice, no matter what the size or orientation of the original image is so I don't think it's an ImageMagik issue. I also think it would be very odd if that feature would only work for a 120 x 78 setting. It seems like photopost crops the image to something smaller than the values set and just blows it up in order to get to that size when the orientation of the source image is a landscape one. Odd that it work's okay for a portrait image by the way, what can you make of that?

[Chuck S]

The command we use is right off the imagemagick site. Not the cropped uniform thumbs can only be used with Imagemagick.

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versus this is the normal command

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notice the only differences really is resize versus size and the gravity center with crop which means we take the image from the center.

ImageMagick: Command-line Options

I am showing the command is valid.

[Jan Klerks]

Is there any way of changing that line so that landscape images get cropped properly when making a uniform squares thumbnail?

[Chuck S]

I am not seeing anything wrong with the line so I am not sure what to tell you there. Seems to fine for me.

[Jan Klerks]

I don' t know how I can be more specific when saying that when having the uniform size thumbnail setting on, and having both height and width set at 164 pixels, the images that are cropped from a landscape orientated images are blurry. Unless you find this ones crystal sharp:

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Original file:

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[Chuck S]

2253 - ReefTalk Gallery

Looks fine to me when I process it using Photopost on my site with a setting of 164 so maybe your imagemagick needs to be upgraded. Could be a bug in your version of Imagemagick.

[Jan Klerks]

^ it indeed does, thanks for testing. I do notice however yours takes out a piece of 164 px x 164 px out of the original size without resizing it first, while mine seems to resize the image first and than takes out a squared bit. Is there any other setting related to this that I need to look at?

[Chuck S]

Not that I am seeing I simply set the uniform size and set it to yes.

I would suspect an issue with your version of mogrify on the server

[Jan Klerks]

We installed the latest version of ImageMagick. If ImageMagick was the problem, that doesn't explain why portrait images get cropped and sharpened properly but landscape images do not.

Why does it take out a but from your image and why does it try to take the maximum out of mine? Must be some sort of setting?

[Chuck S]

Honestly do not know what a but is? Here are my settings

Thumbnail image max width and height in pixels 120

Max allowable image width in pixels 1024

Max allowable image height in pixels 768

Trigger medium graphic height and width 600
An uploaded larger than this will create a medium image of this size.

Photo uploads increment user post count? Yes

Save and display medium and large images? Yes

Quality setting for image resizing/thumbnails? 100

If photo upload width or height exceeds maximums, resize upload down to max dimensions? Yes

Display and extract EXIF information from images? Yes

Maximum multimedia upload size in kB 42000

Degrees to rotate portrait thumbnails? (set to 0 for no rotation) 0
For users of ImageMagick only
Degrees to rotate landscape thumbnails? (set to 0 for no rotation) 0
For users of ImageMagick only
If rotating, long side for mini thumbnail? 0
If rotating your thumbnails, we need to create a mini thumbnail
If rotating, short side for mini thumbnail? 0
If rotating your thumbnails, we need to create a mini thumbnail

Min allowable image width in pixels 0

Min allowable image height in pixels 0


Use Uniform Thumbnails? yes
Can only be used when using IM for imaging.
Uniform thumbnail height? 164

Uniform thumbnail width 164

Enable Flash uploader?
Selects flash uploader is user is registered and flash is installed

[digichickstaff]

Originally Posted by Chuck S

Honestly do not know what a but is?

(I think that was supposed to be "bit.")

The issue is this:

Typically, a thumbnail is generated by resizing (shrinking) the entire image first, then cropping as necessary.

However, what PhotoPost/ImageMagick is currently doing is cropping without first resizing.

It seems most likely that this is an issue with the IM thumbnail generation script that PhotoPost currently uses. I can verify that GD2 is generating thumbnails properly, whereas ImageMagick is not.

[Chuck S]

Digi

The cropping uniform thumbnails does work as I showed above. The issue as seen in this thread probally comes down to possibly imagemagick on that specific server. we have no control over someones image processor install. Our imagemagick crop command comes right from the imagemagick site.

[digichickstaff]

Originally Posted by Jan

I don' t know how I can be more specific when saying that when having the uniform size thumbnail setting on, and having both height and width set at 164 pixels, the images that are cropped from a landscape orientated images are blurry.

I figured out your problem.

It's because the PhotoPost script (the one Chuck mentioned above) first resizes to fit the desired width, then resizes to fit the desired height. Which means that when PhotoPost resizes landscape photos, it's upscaling using this method. (No wonder it's blurry!)

Chuck, I think you'll find the following code to be more graceful (the option flag '^' has been available for this very thing since v.6.3.8-3):

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I've attached some examples for you to compare: 2253thumb2.jpg was generated using the code Chuck posted, while 2253thumb.jpg was generated using the code I've posted here.

To reiterate: the current Uniform Thumbnail script, as applied to landscape-oriented images, shrinks them down too far. It then enlarges the too-small thumbnail before cropping, resulting in a blurry image. The code I've posted here ought to avoid this.

[Chuck S]

well that does not explain why my site using the default code works fine.

I also see nowhere in our code where we shrink anything smaller than a thumbnail size.

I will test what you have posted though.

[Jan Klerks]

@ digichickstaff: thanks for thinking along, much appreciated. Where in which script do I change that IM command line?

[Chuck S]

image-inc.php is the file that has im commands.

[Jan Klerks]

I just changed the code and it works beautiful now. Big thanks again at digichickstaff!

[Chuck S]

Well thats good to hear but it still cant answer I and dont beleive anyone can answer why the normal code works on my server yet not on yours.

Her line differences replace

-strip -resize

with

-thumbnail

and then

-crop

with

-extent