🔍Zoom into any photo far enough and you stop seeing a picture — you start seeing tiny squares. Every Photoshop tool manipulates those squares.
Core Concept
What Is a Pixel?
🟧
One Pixel
A single square of one solid color. No gradients, no blending — just one unique color value stored as Red, Green, Blue numbers.
×
📷
24 Megapixels
24,000,000 of those tiny colored squares captured at the shutter press. That's what fills your camera's sensor grid.
💡One megapixel = one million pixels. Every Photoshop tool — every filter, brush, and adjustment — is just manipulating which color goes in each square.
Core Concept
Resolution — Two Numbers to Memorize
🖥️
Screen / Web
72 PPI
Monitors and web images. Only pixel dimensions matter for screen (e.g., 2000px wide). The PPI number itself is largely irrelevant online.
72 ppi
🖨️
Print
300 PPI
Professional print quality. Same 6,000px-wide photo prints 20" at 300 ppi — or a blurry 83" at 72 ppi. Same pixels, different density.
300 ppi
📐
Key Insight
Same Pixels
Resolution only controls how tightly pixels are packed on paper. It does not change how many pixels exist in the file.
Image > Image Size
🧠72 ppi for screen and web. 300 ppi for print. Those are the only two numbers you need to know.
Core Concept
Image Size vs Canvas Size
🎨
Image Size
Resizes the painting. Scales actual photo pixels up or down. Upsizing creates new (interpolated) pixels. Downsizing permanently discards pixels.
Image → Image Size
vs
🖼️
Canvas Size
Resizes the frame. Changes the workspace without scaling the photo. Enlarging adds transparent or filled space around it. Shrinking crops it.
Image → Canvas Size
🖼️Image Size = resize the painting. Canvas Size = resize the frame the painting sits in. They are not the same thing.
Core Concept
Raster vs. Vector
🟦
Raster (Pixels)
Fixed grid of colored squares. Scale up too far → pixelation. Every photo you shoot is raster. Photoshop's core strength. Resolution is baked in at capture.
vs
🔷
Vector (Math)
Mathematical paths and coordinates. Scales to any size — postage stamp to billboard — and stays razor-sharp forever. Illustrator's home. Photoshop has vector tools but its core is raster.
⚠️Photoshop is primarily a raster editor. When you rasterize a shape or type layer, it becomes pixels permanently. Pay attention to that warning dialog.
Core Concept
Bit Depth — How Much Color Each Pixel Holds
📷
8-Bit
16.7M Colors
Fine for final exported files (JPEG). Not ideal for heavy editing — limited headroom when pushing Curves and color work hard.
Final export only
⭐
16-Bit
Billions
Use this while editing. More color data = smoother gradients, less banding when you push adjustments to the extreme.
★ Edit in this
🌟
32-Bit
HDR / Float
For HDR merging and specialized compositing. Most filters don't work in 32-bit. Specialized use only.
HDR / Specialized
🔧Set 16-bit before editing: Image → Mode → 16 Bits/Channel. More data means more room to push edits without visible quality loss.
Core Concept
RGB vs CMYK — Stay in RGB
🖥️
RGB — Your Mode
Red · Green · Blue
✓ Screens & monitors
✓ Photography workflows
✓ Camera captures in RGB
✓ Web & social media
✓ Home photo printing
Stay here your entire workflow.
vs
🖨️
CMYK — Not Yours
Cyan · Magenta · Yellow · Black
⚠ Commercial offset presses
⚠ Magazines & catalogs
⚠ Your print lab handles this
⚠ Converting loses color data
RGB → CMYK is a one-way trip.
⚠️Unless you're sending files to a commercial offset printer, stay in RGB for your entire photography workflow. Your photo lab converts automatically.
File Formats
Know Your File Formats
PSD
Photoshop Document — Your Working File
Keeps all layers, masks, adjustment layers, smart objects, and type fully editable. Always save your work as PSD. This is your master file — never overwrite it with a JPEG.
TIFF
Tagged Image File — Lossless & Print-Ready
No quality loss on save. Larger file size. Excellent for print delivery and archival. Great for handing files off to printers.
JPG
JPEG — For Sharing and Web Only
Lossy compression — discards image data every time you save. Flattens all layers. Small file, universal compatibility. Export JPEG at the end of your workflow, not during.
PNG
PNG — Lossless with Transparency
Preserves transparency (alpha channel). Lossless. Larger than JPEG. Perfect for graphics, logos, and images that need transparent backgrounds.
💾The rule: PSD to edit. TIFF for print handoff. JPEG only at the very end. Never save your working file as a JPEG.
Workflow
4 Ways Into Photoshop
1
File → Open (Cmd/Ctrl + O)
Classic method. Navigate to your file in the system dialog. RAW files automatically route through Camera Raw first.
2
Drag & Drop onto the Photoshop Icon
Drag any file onto the Photoshop icon in your Dock (Mac) or Taskbar (PC). Fast and tactile. Works exactly like File > Open.
3
Adobe Bridge
The file browser built for Photoshop. Browse, rate, and filter photos — then double-click to open. RAW files still route through Camera Raw.
4
Lightroom → Edit In → Adobe Photoshop ⭐ Most Common
Right-click a photo in Lightroom Classic → Edit In → Edit in Adobe Photoshop. Opens with your Lightroom edits already applied. Changes save back to Lightroom automatically.
→If the file is RAW, any of these routes automatically opens Camera Raw first for global adjustments before the image enters Photoshop.
Workflow
Lightroom & Photoshop — They Collaborate
📚
Lightroom — Step 1
✓ Import & catalog all photos
✓ Cull and rate images
✓ Global exposure adjustments
✓ Color grading & tone curves
✓ Noise reduction & sharpening
✓ Export for web & print
Start here every time.
→
🔬
Photoshop — Step 2
✓ Remove objects (pixel-level)
✓ Composite two images
✓ Complex masking & selections
✓ Skin retouching
✓ Adding text & graphics
✓ Anything Lightroom can't do
Only when Lightroom isn't enough.
→The workflow: Lightroom first → Photoshop when needed → save → back to Lightroom automatically. They don't compete. They collaborate.
Lesson Recap
3 Things to Remember
1
Photoshop Thinks in Pixels
Every photo is a grid of colored squares. Every tool manipulates those squares. This foundation explains every behavior.
2
300 PPI Print · 72 PPI Screen
Resolution controls print size, not screen quality. Memorize these two numbers and you'll never have a bad print again.
3
16-Bit to Edit · PSD to Save · JPEG at the End
Set 16-bit mode before editing. Save your working file as PSD always. Export JPEG only for the final output.
🧠These three habits separate confident Photoshop users from frustrated ones. Lock them in on day one.
Your Challenge
🎯
Before Lesson 02
Open a photo in Photoshop and run these quick checks. Takes 5 minutes and builds real muscle memory.
📐 Open Image → Image Size — note the pixel dimensions and resolution
🎨 Check Image → Mode — is it RGB? Is it 8-bit or 16-bit?
🔍 Zoom to 3200% — find the individual pixels and hover to see RGB color values
💾 Save As → PSD format — confirm layers are preserved in the file
I know what a pixel is and what PPI means
I'll set my file to 16-bit before editing
I'll save working files as PSD and export JPEG only at the end
Up Next
Lesson PS-02 — Photoshop
The Workspace: Panels, Tools & Making Photoshop Yours
150 tools. 40 panels. You'll use about 12 of them. Let's find those 12 — and set up a workspace that actually makes sense for photographers.