GD Chapter 9 — Adobe Photoshop

9.1Introduction of Adobe Photoshop

Adobe Photoshop (Ps) is a raster graphics editor created by Thomas and John Knoll in 1988 and acquired by Adobe in 1989. It is the industry standard for photo editing, digital painting, compositing, and any work where pixels — not paths — are the unit of work.

What Photoshop is for

Photo editing and retouching.
Colour correction and enhancement.
Compositing multiple images into one.
Digital painting and illustration.
Web graphics, mockups.
Preparing photos for print (CMYK conversion, sharpening).

Workspace

Tools panel (left) — Move, Selection, Brush, Clone, Crop, Type, Shape.
Options bar (top) — settings for the current tool.
Panels (right) — Layers, Channels, Paths, Adjustments, Swatches, Colour, History.
Canvas — the image area.

Raster basics

Image = grid of pixels.
Resolution — pixels per inch (PPI). 72 for web, 300 for print.
Colour modes — RGB (screen), CMYK (print), Grayscale, Bitmap, Lab.
Bit depth — 8-bit is standard; 16-bit for high-quality edits.

Photoshop = the darkroom of a photographer who never sleeps. Dodge, burn, crop, airbrush, composite — everything a film photographer once did in a red-lit room, but with undo.

9.2Know about Selection Tools

Selections define the area of an image you want to edit. Everything outside a selection is protected from your changes.

Key selection tools

Marquee tools (M) — Rectangular, Elliptical. Simple geometric selections.
Lasso (L) — freehand; Polygonal Lasso for straight-edge; Magnetic Lasso snaps to edges.
Magic Wand (W) — selects pixels of similar colour.
Quick Selection (W) — paints the selection; auto-expands to similar areas.
Object Selection (W) — draw a box; AI finds the subject.
Select Subject / Select Sky — one click AI selections.
Pen tool (P) + Make Selection — the most precise; draws a path then converts to selection.

Selection modifiers

Add to selection — Shift.
Subtract — Alt/Option.
Intersect — Shift+Alt.
Feather — softens the selection edge.
Refine Edge / Select and Mask — perfect selections of hair, fur.
Inverse (Shift+Ctrl+I) — flip the selection.
Deselect (Ctrl+D).

A good selection is 80% of a good edit. Sloppy selection = halos around the subject = obvious fake. Time spent on the selection always pays back.

9.3Know about Clone Stamp and Eraser Tools

Clone Stamp (S)

Copies pixels from one area to another.
Alt-click on the source → then paint elsewhere to copy.
Used to remove blemishes, unwanted objects, repair damaged photos.
Options: brush size, hardness, opacity, flow, alignment.

Healing tools (related)

Spot Healing Brush (J) — one-click removal of small blemishes.
Healing Brush — like Clone Stamp but blends texture/lighting.
Patch tool — select an area, drag to a clean one.
Content-Aware Fill — AI replaces a selection with surrounding content.

Eraser tools (E)

Eraser — paints over pixels with the background colour (or transparency if on a layer with no background).
Background Eraser — erases only the colour you click; preserves the subject.
Magic Eraser — one-click erase of similar-coloured areas (like Magic Wand + Delete).
Note: layer masks are usually safer than erasing — non-destructive.

Clone Stamp = the Photoshop doctor. Pimple gone, power line gone, ex-boyfriend gone. Use responsibly — press photography has ethical limits.

9.4Image Retouching (Brightness, Contrast, Colour Balance)

Brightness / Contrast

Image → Adjustments → Brightness/Contrast.
Quick tool: brightness = overall light/dark; contrast = difference between light and dark.
For finer control, use Levels or Curves.

Levels (Ctrl+L)

Histogram with 3 sliders: black point, mid-tones (gamma), white point.
Drag black slider in to deepen shadows; white in to brighten highlights.

Curves (Ctrl+M)

Most powerful tone-adjustment tool.
Drag the curve up to brighten, down to darken; S-curve adds contrast.
Per-channel curves adjust individual colours.

Colour Balance (Ctrl+B)

Three sliders: Cyan↔Red, Magenta↔Green, Yellow↔Blue.
Apply separately to shadows, mid-tones, highlights.
Useful for warming/cooling a photo, fixing colour casts.

Other common adjustments

Hue / Saturation (Ctrl+U) — shift hue, boost or desaturate colour.
Vibrance — smarter saturation; doesn't over-saturate skin tones.
Exposure — for RAW-like exposure correction.
Shadow/Highlight — recover details in blown highlights or crushed shadows.
Black & White — customised grayscale conversion.
Photo Filter — simulate traditional warming/cooling filters.

Non-destructive workflow

Always use Adjustment Layers (bottom of Layers panel) instead of direct Image → Adjustments.
You can toggle, edit, or delete them any time without damaging the original pixels.

9.5Knowledge of File Extensions (JPEG, TIFF, PNG, PDF, PSD)

Format	Type	Best for	Notes
JPEG / JPG	Raster, lossy compression	Photos on web and general use	Small file; quality loss each save; no transparency
TIFF	Raster, lossless	Print production, archival	Large file; preserves all quality; supports layers & channels
PNG	Raster, lossless	Web graphics, logos, anything with transparency	Supports alpha channel; larger than JPEG for photos
PDF	Document / layout	Print-ready files, multi-page documents, sharing	Preserves vectors + fonts; viewable anywhere
PSD	Photoshop native	Active work files with layers	Layers, masks, adjustment layers, smart objects all preserved

Other useful formats

GIF — 256 colours, supports animation.
WebP — modern web format; smaller than JPG/PNG.
RAW (CR2, NEF, ARW, DNG) — camera's unprocessed file; maximum edit latitude.
BMP — old Windows format, uncompressed.
EPS — older vector+raster; for legacy presses.

JPG = photo. PNG = logo with transparent background. TIFF = "send to the printer." PSD = "I'm still working on this." Memorize this line and you'll never email the wrong format again.

9.6Working with Layer

Layers are transparent sheets stacked on top of each other. Each can hold its own image or effect. The top layer hides layers beneath where it has content. Photoshop's power basically IS the layer system.

Core layer operations

New layer — Layer → New → Layer (Ctrl+Shift+N).
Duplicate — Ctrl+J.
Delete — drag to trash icon.
Rename — double-click name.
Reorder — drag up/down in Layers panel.
Group — Ctrl+G; folders for organizing.
Link — move multiple layers together.
Merge — Merge Down (Ctrl+E), Merge Visible, Flatten Image.

Layer types

Pixel layer — regular image data.
Background layer — the locked bottom; double-click to convert to normal layer.
Type layer — editable text.
Shape layer — vector shapes.
Adjustment layer — non-destructive tone/colour adjustments affecting layers below.
Smart Object — a container; edit the source non-destructively; scale without quality loss.
Fill layer — solid colour, gradient, or pattern.

Opacity, Fill, Blend modes

Opacity — how see-through the whole layer is (including effects).
Fill — affects pixels but preserves layer effects.
Blend modes — how a layer mixes with layers below. Common: Multiply (darkens), Screen (lightens), Overlay (contrast), Soft Light (gentle contrast).

Layer masks

Add a mask (icon in Layers panel) — paint with black to hide parts, white to reveal.
Non-destructive alternative to the Eraser.
Clipping mask — a layer only shows where the layer directly below has pixels.
Vector mask — precise mask using a shape/path.

Layers = transparent slides stacked on a projector. Pull one out, the whole scene changes. Shuffle their order, the composition changes. Photoshop without layers = paint on a single wall.

9.7Layer Style

Layer Styles are preset effects applied to an entire layer — drop shadow, glow, stroke, bevel, gradient overlay. Double-click a layer to open the Layer Style dialog.

Common styles

Drop Shadow — classic offset shadow.
Inner Shadow — shadow inside edges.
Outer Glow / Inner Glow — soft light around edges.
Bevel & Emboss — 3D look with light and shade.
Satin — interior shading.
Colour Overlay — a flat colour covering the layer.
Gradient Overlay — gradient applied to the layer.
Pattern Overlay — a repeating pattern filling the layer.
Stroke — outline around the layer's contents.

Key behaviours

Non-destructive — toggle on/off any time.
Copy layer style → paste on another layer (right-click on layer).
Scale effects when resizing a document (Layer → Layer Style → Scale Effects).
Save a combination as a Style preset for reuse across projects.

🖼️ Adobe Photoshop