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Image will be shrink in the case of automatic JPEG and PNG format to upload the image. 
There are the following features in isShrinker WordPress Plugin.
Can specify the maximum file size. 
Keep aspect ratio. 
Convert image inclination from inclination information of image
If you upload, such as iPhone app slope of image because reduced after correction 
it appears in the blog exactly as it appears in the iPhone.
The maximum file size of the image is 50KB by default 
Length of the long side of the image is 640px by default 
And it is with, but you can change from the management screen of WordPress.
Upload png image ‘watermark.png’ to plugin directory and then watermark will be enable. 
Watermark add on right bottom of image. 
If watermark enabled water mark transparency setting is enable.
<h3>Arbitrary section 1</h3>

isShrinker

When uploading, it will shrink the image automatically. The feature is  keeping the aspect ratio and  maximum file size can be specified.

ShortPixel

reSmush.it

The reSmush.it Image Optimizer is a free WordPress image compressor and optimizer plugin which allows you to smush your website’s images so that they load faster. 
The plugin is super easy to use (just 2 clicks!), supports JPG, PNG and GIF image formats and can be used to bulk optimize current (past) images and automatically optimize all new images. 
You can also adjust the optimization levels and exclude certain images. 
Since its launch more than 9 years ago, <a href="https://resmush.it" rel="nofollow ugc">reSmush.it</a> has become the preferred choice for WordPress image optimization as it allows you to smush the images for free. 
reSmush.it image optimization service works on <a href="https://resmush.it/tools/" rel="nofollow ugc">various CMS platforms</a> (WordPress, Drupal, Joomla, Magento, Prestashop, etc.) and is used by more than 400,000 websites worldwide. 
reSmush.it has earned the reputation of being the best free, fast and easy image optimization plugin out there 🙂
Features: 
– Free bulk image compressor 
– Automatic image optimization on upload 
– Keep or remove EXIF data 
– Image quality selector 
– Exclude images from optimization 
– Powerful and free image optimizer API 
– Customizable settings for image quality 
– Automatic image optimization with CRON 
– Backup and restore original images 
– Image statistics 
– File logging for developers
Other plugins by <a href="https://shortpixel.com" rel="nofollow ugc">ShortPixel</a>:
<ul>
<li><a href="https://wordpress.org/plugins/fastpixel-website-accelerator/" rel="ugc">FastPixel Caching</a> – WP Optimization made easy</li>
<li><a href="https://wordpress.org/plugins/shortpixel-image-optimiser/" rel="ugc">ShortPixel Image Optimizer</a> – Image optimization & compression for all the images on your website, including WebP & AVIF delivery</li>
<li><a href="https://wordpress.org/plugins/shortpixel-adaptive-images/" rel="ugc">ShortPixel Adaptive Images</a> – On-the-fly image optimization & CDN delivery</li>
<li><a href="https://wordpress.org/plugins/enable-media-replace/" rel="ugc">Enable Media Replace</a> – Easily replace images or files in Media Library</li>
<li><a href="https://wordpress.org/plugins/regenerate-thumbnails-advanced/" rel="ugc">reGenerate Thumbnails Advanced</a> – Easily regenerate thumbnails</li>
<li><a href="https://wordpress.org/plugins/resize-image-after-upload/" rel="ugc">Resize Image After Upload</a> – Automatically resize each uploaded image</li>
<li><a href="https://wordpress.org/plugins/wp-svg-images/" rel="ugc">WP SVG Images</a> – Secure upload of SVG files to Media Library</li>
</ul>

reSmush.it : The original free image compressor and optimizer plugin

the plugin is great, but the service itself is remote so you depend on the network, this causes many stability issues and in the past weeks ițs been horrible.

many stability

Unfortunately I had a lot of problems with resmush.it. Even running it on a fairly new and clean website with few other plugins. 

1. Resmush.it constantly had problems connecting to a server.

2. When I tried uploading an image I sometimes had to wait for minutes before smushed it. I don't know whether it had anything to do with the server connection issue.

3. When I tried to recreate all images it broke the site after which I had to install the site from a backup. The fact that there is an admin notice saying to backup the whole site before doing that only means that this is a common issue.

All in all I had very bad experience with the plugin and I don't recommend it to anyone.

Only problems

reSmush.it is the FREE image compressor and optimizer plugin - use it to optimize your images and improve the SEO and performance of your website.

isShrinker vs reSmush.it : The original free image compressor and optimizer plugin