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We have created a module to create BlurHash strings for images while uploading in ProcessWire. This blurry images will be saved in the database because they are very small (20-30 characters) and can be used for Data-URL's  as placeholders for image-lazy loading.

https://github.com/blue-tomato/ImageBlurhash

E.g. where we use this in production:

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Hi @Markus (Blue Tomato)

I also think this is awesome!

I wanted to try it, but I have some strange problems getting in running. I don't know if it is only me, but nevertheless I wanted to post here. Maybe someone can help. 

One strange issue at first: 
When an image is saved, the hash is not stored in the db table (although the "insertBlurhash" function returns true).

And the second issue comes when calling the "getBlurhashDataUri" function. (I manually inserted the hash string to the database, because of the before mentioned issue). 
Then I'll get based on the image up to several 100-thousands warnings like "PHP Notice: Undefined offset: 208 in .../ImageBlurhash/ImageBlurhash.module.php:122".

Maybe there is some config issue on my side or anything else I missed. But maybe someone has an idea. 

Btw. I checked it both on Windows and Linux with PHP 7.2 and latest ProcessWire dev version.

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8 hours ago, androbey said:

Hi @Markus (Blue Tomato)

I also think this is awesome!

I wanted to try it, but I have some strange problems getting in running. I don't know if it is only me, but nevertheless I wanted to post here. Maybe someone can help. 

One strange issue at first: 
When an image is saved, the hash is not stored in the db table (although the "insertBlurhash" function returns true).

And the second issue comes when calling the "getBlurhashDataUri" function. (I manually inserted the hash string to the database, because of the before mentioned issue). 
Then I'll get based on the image up to several 100-thousands warnings like "PHP Notice: Undefined offset: 208 in .../ImageBlurhash/ImageBlurhash.module.php:122".

Maybe there is some config issue on my side or anything else I missed. But maybe someone has an idea. 

Btw. I checked it both on Windows and Linux with PHP 7.2 and latest ProcessWire dev version.

Hi @androbey,

Hm, sounds strange. What does the createBlurhash return before insertBlurhash is executed?

I think the second issue depends on the first issue. Something is wrong with the creation of the blurhash - I guess it makes an corrupt image. Do you have an example image for me? Maybe I could reproduce it on my system.

FYI: currently in runs on our production server with php 7.4, mysql 5.7 and latest processwire dev version on an debian buster machine

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Hi @Markus (Blue Tomato),

thanks for your reply. 

I tried again with an image found on the web, but no luck.

createBlurhash for this particular image returns "LdLx}oxdzpwN}tNHNsbI#laxS}f*" (so at least seems to work?), but is not stored in the db.

Image for this test: https://pixabay.com/get/53e2d14b4b5aaf14f6da8c7dda35367b1c3ddce05152774a_1280.jpg

Maybe I can check tomorrow with a different test setup.

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Hi @androbey,

The whole SQL thing let me rethink how I store the blurhashs. I discovered the Pagefile->fildedata API and refactored the module to use this instead of the custom SQL column in the image field table. At the first try it looks that everything works well. Please test again ?

https://github.com/blue-tomato/ImageBlurhash/releases/tag/2.0.0

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Hi @Markus (Blue Tomato),

thank you for the update. 

I tested the new version and the generation and storage of the blurhashs works fine! On a side node, I find it still strange that the custom SQL did not (always) work.
After upgrading my issue with "undefinded offset" was still present. I checked the used PHP Blurhash library and your code and I adjusted lines 108 and 109 and replaced $height and $width with $calcHeight and $calcWidth.

This solves the issue (no more notices), but I don't know if it has any drawbacks..

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10 hours ago, androbey said:

Hi @Markus (Blue Tomato),

thank you for the update. 

I tested the new version and the generation and storage of the blurhashs works fine! On a side node, I find it still strange that the custom SQL did not (always) work.
After upgrading my issue with "undefinded offset" was still present. I checked the used PHP Blurhash library and your code and I adjusted lines 108 and 109 and replaced $height and $width with $calcHeight and $calcWidth.

This solves the issue (no more notices), but I don't know if it has any drawbacks..

There was one problem, that the Hook was sometimes executed before the entry was saved to the database. So the blurhash query did not found the entry. And the second problem was an encoding issue with some characters int he blurhash.

Strange... this undefinded offset did never happen in my side. But I will check if $calcHeight and $calcWidth works on my side and will change this in the repo

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Very interesting! This is definitely the cleanest and most straight-forward option for generating low-quality image placeholders. Thanks for releasing ?

Two questions  @Markus (Blue Tomato):

1. How is performance for generating the data URIs? Do you generate them on the fly for every request or do you store the final LQIP data URI somewhere as well? My current implementation puts the tiny 200byte LQIP file alongside the source image; I wonder what's better here: generating in memory or reading from disk.

2. I remember you releasing a similar tool for generating SVG shapes — did you stop using that in favor of the blurhash or are you using both in parallel?

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4 hours ago, d'Hinnisdaël said:

Very interesting! This is definitely the cleanest and most straight-forward option for generating low-quality image placeholders. Thanks for releasing ?

Two questions  @Markus (Blue Tomato):

1. How is performance for generating the data URIs? Do you generate them on the fly for every request or do you store the final LQIP data URI somewhere as well? My current implementation puts the tiny 200byte LQIP file alongside the source image; I wonder what's better here: generating in memory or reading from disk.

2. I remember you releasing a similar tool for generating SVG shapes — did you stop using that in favor of the blurhash or are you using both in parallel?

1. Currently the data URIs are not cached or saved somewhere. They are generated on the fly - I did not see huge performance issues yet - we use ProCache for caching the whole HTML.

2. Yes we used "SVG Primitives". But the setup for this was too much work to maintain. Primitive itself was only written in Golang and the generation of the images took a huge amount of server resources.

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  • 5 weeks later...
  • 3 weeks later...
On 7/27/2020 at 12:05 PM, gornycreative said:

I get a php notice undefined offset in line 110 on the main module.php file

I got this too, and it seems to happen when passing fraction values to getBlurhashDataUri() - these were calculated for an image ratio (e.g. $height = $width * 0.35).

If you're doing this, try passing whole numbers, or rounding the calculated dimension first (using floor, round, ceil functions):

$image->getBlurhashDataUri(95, floor(95 * $ratio));

 

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On 8/13/2020 at 12:02 PM, houseofdeadleg said:

Would love to try this module as my site's very image heavy, but is there any alternative way to install it without having to use Composer?

Yes it's possible. You can download it from the pw module directory but you also have to install https://github.com/kornrunner/php-blurhash manually and include it.

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On 8/13/2020 at 12:02 PM, houseofdeadleg said:

Would love to try this module as my site's very image heavy, but is there any alternative way to install it without having to use Composer?

Maybe worth a try: https://php-download.com/

PS: https://stackoverflow.com/questions/40545795/how-do-i-install-composer-php-packages-without-composer

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On 8/12/2020 at 11:52 PM, Craig said:

I got this too, and it seems to happen when passing fraction values to getBlurhashDataUri() - these were calculated for an image ratio (e.g. $height = $width * 0.35).

If you're doing this, try passing whole numbers, or rounding the calculated dimension first (using floor, round, ceil functions):


$image->getBlurhashDataUri(95, floor(95 * $ratio));

 

Thx, I pushed a fix for this by rounding width and height directly in getBlurhashDataUri

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  • 1 month later...
1 hour ago, bernhard said:

Hmmm, can you send me some of your original uploaded images which makes this problem?

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On 9/18/2020 at 11:22 PM, bernhard said:

I'm getting the error with the default Windows desert sample image when using this:


$hash = $page->pic()->getBlurhashDataUri($page->pic()->width, 100);

 

Desert.jpg

I will take a look into it this week. In the meanwhile you try to create the blurhash based on a smaller size.

I make this on also every blurhash pic on blue tomato

E.g.

// original pic size: 500/200
$hash = $page->pic()->getBlurhashDataUri(50, 20);
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