Image transformations in Supabase - Mini Project: Build & Apply

Image transformations

📖 Scenario: You are building a simple web app that shows user profile pictures stored in Supabase storage. You want to apply image transformations like resizing and format conversion on these images before displaying them.

🎯 Goal: Learn how to use Supabase's image transformation URL parameters to resize and convert images stored in Supabase storage buckets.

📋 What You'll Learn

Create a Supabase storage bucket URL string for an image

Add a transformation configuration variable for resizing

Apply the transformation parameters to the image URL

Complete the final transformed image URL with format conversion

💡 Why This Matters

🌍 Real World

Image transformations are commonly used in web apps to optimize images for faster loading and better user experience.

💼 Career

Knowing how to manipulate image URLs in cloud storage services like Supabase is useful for frontend and backend developers working with media content.

1

Create the base image URL

Create a variable called baseImageUrl and set it to the exact string "https://xyzcompany.supabase.co/storage/v1/object/public/avatars/user123.png".

Supabase

// Create a variable called baseImageUrl with the exact URL string
// Your code here

Hint

This URL points to the public image stored in the Supabase storage bucket named avatars.

2

Add a resize transformation config

Create a variable called resizeParams and set it to the exact string "?width=150&height=150" to resize the image to 150 by 150 pixels.

Supabase

const baseImageUrl = "https://xyzcompany.supabase.co/storage/v1/object/public/avatars/user123.png";
// Create a variable called resizeParams with the string "?width=150&height=150"
// Your code here

Hint

The query parameters width and height control the image size.

3

Combine base URL and resize parameters

Create a variable called resizedImageUrl and set it to the concatenation of baseImageUrl and resizeParams.

Supabase

const baseImageUrl = "https://xyzcompany.supabase.co/storage/v1/object/public/avatars/user123.png";
const resizeParams = "?width=150&height=150";
// Combine baseImageUrl and resizeParams into resizedImageUrl
// Your code here

Hint

Use the + operator to join the strings.

4

Add format conversion to the image URL

Create a variable called finalImageUrl and set it to the concatenation of baseImageUrl and the exact string "?width=150&height=150&format=webp" to resize and convert the image to WebP format.

Supabase

const baseImageUrl = "https://xyzcompany.supabase.co/storage/v1/object/public/avatars/user123.png";
const resizeParams = "?width=150&height=150";
const resizedImageUrl = baseImageUrl + resizeParams;
// Create finalImageUrl with resizing and format conversion to webp
// Your code here

Hint

Append &format=webp to the query parameters for format conversion.

Practice

1. What is the main purpose of image transformations in Supabase storage?

easy

A. To change how images look without modifying the original file

B. To permanently delete the original image after editing

C. To convert images into text files

D. To upload images faster by compressing them automatically

Solution

1. Step 1: Understand image transformation concept

   Image transformations modify the appearance of images dynamically without changing the original stored file.

2. Step 2: Identify the purpose in Supabase

   Supabase uses transformations to resize, crop, or add effects on the fly, keeping the original image intact.

3. Final Answer:

   To change how images look without modifying the original file -> Option A

4. Quick Check:

   Image transformations = change appearance only [OK]

Hint: Image transformations do not alter the original file [OK]

Common Mistakes:

• Thinking transformations delete or overwrite original images
• Confusing transformations with file format conversion
• Assuming transformations speed up upload automatically

2. Which URL query parameter correctly resizes an image to 300 pixels wide in Supabase?

easy

A. ?size=300

B. ?resize=300

C. ?width=300

D. ?w=300

Solution

1. Step 1: Recall Supabase image resize syntax

   Supabase uses the parameter w to specify width in pixels for resizing images.

2. Step 2: Match correct parameter

   The correct query parameter to resize width to 300 pixels is ?w=300.

3. Final Answer:

   ?w=300 -> Option D

4. Quick Check:

   Resize width = ?w=number [OK]

Hint: Use ?w= for width resizing in Supabase URLs [OK]

Common Mistakes:

• Using ?width= or ?resize= which are invalid
• Confusing size with width parameter
• Omitting the question mark in URL

3. What will be the result of accessing the URL https://example.supabase.co/storage/v1/object/public/images/photo.jpg?w=200&h=100&fit=crop?

medium

A. The image will be resized to 200x100 pixels and cropped to fit exactly

B. The image will be resized to 200x100 pixels but stretched without cropping

C. The image will remain original size ignoring parameters

D. The URL will cause an error due to invalid parameters

Solution

1. Step 1: Analyze URL parameters

   The URL includes w=200 (width), h=100 (height), and fit=crop which crops the image to fit exactly the given dimensions.

2. Step 2: Understand transformation behavior

   Supabase will resize the image to 200 pixels wide and 100 pixels tall, cropping parts if needed to maintain aspect ratio.

3. Final Answer:

   The image will be resized to 200x100 pixels and cropped to fit exactly -> Option A

4. Quick Check:

   Resize + crop = exact fit size [OK]

Hint: fit=crop crops image to exact width and height [OK]

Common Mistakes:

• Assuming fit=crop stretches image without cropping
• Ignoring height parameter h
• Thinking parameters cause errors

4. You tried to resize an image using ?w=abc in the URL but it did not work. What is the likely problem?

medium

A. The parameter should be ?width=abc instead

B. The width parameter must be a number, not letters

C. Supabase does not support resizing images

D. You need to add &fit=stretch to resize properly

Solution

1. Step 1: Check parameter value type

   The width parameter w expects a numeric value representing pixels, not letters.

2. Step 2: Identify error cause

   Using abc as value is invalid and causes the resize to fail.

3. Final Answer:

   The width parameter must be a number, not letters -> Option B

4. Quick Check:

   Width value must be numeric [OK]

Hint: Width and height values must be numbers [OK]

Common Mistakes:

• Using text instead of numbers for size
• Changing parameter name incorrectly
• Assuming resizing needs extra fit parameter

5. You want to display a thumbnail of an image that is exactly 150x150 pixels, cropped to center, and with a grayscale effect. Which URL query parameters should you use?

hard

A. ?w=150&h=150&fit=crop&grayscale=true

B. ?width=150&height=150&crop=center&effect=grayscale

C. ?w=150&h=150&fit=crop&grayscale=1

D. ?w=150&h=150&fit=contain&grayscale=1

Solution

1. Step 1: Set size and cropping parameters

   Use w=150 and h=150 to set width and height, and fit=crop to crop the image to exact size centered.

2. Step 2: Apply grayscale effect correctly

   Supabase uses grayscale=1 to apply grayscale effect, not true.

3. Final Answer:

   ?w=150&h=150&fit=crop&grayscale=1 -> Option C

4. Quick Check:

   Crop + grayscale=1 for exact grayscale thumbnail [OK]

Hint: Use grayscale=1, not true, for grayscale effect [OK]

Common Mistakes:

• Using true instead of 1 for grayscale
• Using fit=contain instead of fit=crop
• Using wrong parameter names like width or effect