> For the complete documentation index, see [llms.txt](https://railsgirlskc.gitbook.io/workshop-guide/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://railsgirlskc.gitbook.io/workshop-guide/part-6-create-thumbnails-with-carrierwave.md).
# Part 6: Create Thumbnails with CarrierWave
**Coach**: Explain what specifying the image width in HTML at the end of Part 4 does and how it differs from resizing images on the server.
### 1. Installing ImageMagick
* OS X: run `brew install imagemagick`. If you don’t have the brew command, you can [install Homebrew here](https://brew.sh/). After installation, close and reopen the terminal to make sure imagemagick is loaded correctly
* Windows: download and run the [ImageMagick installer](http://www.imagemagick.org/script/download.php#windows) (use the first *download* link). In the installation wizard, make sure you check the checkbox to install legacy binaries. After installation, close and reopen GitBash, and Command Prompt with Ruby and Rails.
* Linux: On Ubuntu and Debian, run `sudo apt-get install imagemagick`. Use the appropriate package manager instead of `apt-get` for other distributions. After installation, close and reopen the terminal to make sure imagemagick is loaded correctly
**Coach**: What is ImageMagick and how is it different from libraries/gems we used before?
Open `Gemfile` in the project and add
```ruby
gem 'mini_magick', '4.9.5'
```
under the line
```ruby
gem 'carrierwave'
```
In the Terminal run:
```
bundle
```
### 2. Telling our app to create thumbnails when an image is uploaded
Open `app/uploaders/picture_uploader.rb` and find the line that looks like this:
```ruby
# include CarrierWave::MiniMagick
```
Remove the `#` sign.
**Coach**: Explain the concept of comments in code.
Below the line you just changed, add:
```ruby
version :thumb do
process :resize_to_fill => [50, 50]
end
```
The images uploaded from now on should be resized, but the ones we already have weren’t affected. So edit one of the existing ideas and re-add a picture.
### 3. Displaying the thumbnails
To see if the uploaded picture was resized open `app/views/ideas/index.html.erb`. Change the line
```ruby
<%= image_tag idea.picture_url, width: '100%' if idea.picture.present? %>
```
to
```ruby
<%= image_tag idea.picture_url(:thumb) if idea.picture.present? %>
```
Take a look at the list of ideas in the browser to see if the thumbnail is there. You will probably need to re-upload the images for the new thumbnails to generate.
