Images II

Images II

Art 311 Lecture 09

J Parker

Fall 2010

Tools

Because image files are not text, we can’t usually edit them like documents.

We need special programs that read and write image files, and can offer a user the ability to manipulate pixels, regions, colours, and files.

The best known one is Photoshop. Others include Paint, LView, Gimp, and XV.

Paint

Comes with Windows, a basic program.

Paint

Has a limited number of tools.

Free-form selectEraser

Pick colourPencil

AirbrushLine

RectangleEllipse

Select regionFill

MagnifyBrush

TextCurve

PolygonRounded Rectangle

Paint

Let’s do a small project …

Paint

First some basic shapes

Paint

Edit a bit, some freehand with pencil

Paint

Finish visor – rounded rectangle + freehand

Paint

Top of head, then colour it.

Paint

Colour palette can be changed.

Paint

Size too – Image->Attributes

Photoshop

Probably the most popular image editor.

- Used to clean up family photos

- Used to ‘fake’ images.

- Used (improperly, I think) for forensic analysis.

Part of Adobe CS3 and CS4, it can be expensive ($600).

Photoshop

A key aspect of photoshop is its use of layers.

A layer is a more or less transparent canvas on which any image can be placed.

It’s like using overhead transparencies – draw parts of a scene on each, then overlay them.

Photoshop

Photoshop

Tools!

Marquee - Click and drag to select part of the image

Move - Click and drag to move a selected area or an

entire layer.

Crop - Click and drag to specify area to crop. Press Enter key to crop or Escape key to cancel.

Type - Click the image with the type tool where you want to add type. Hand - Drag with the hand tool to move around an image

Photoshop

Palettes -

Show the basic ingredients you are using at the moment.

Photoshop – Common operations

Read a file:

Click File > Open and then give a file name.

Click File > New and specify a new file:

Photoshop – Modes

24 bit colour Greyscale mode

Bitmap Colourmap

Photoshop – Clone

The clone tool ( ), also called the rubber stamp, allows you to remove imperfections such as dust and scratches by covering them with samples of nearby pixels. For best results, zoom in close and use a small brush.

Photoshop – Healing The healing brush attempts to take the texture from the

sample without affecting the brightness of the area to which it is applied. In some cases this is more effective than the clone tool. The following is shows the same correction as above, only this time done with the healing brush tool. The blemish appears to be somewhat less noticeable.

Photoshop – Contrast

Image>Adjust>Levels

Contrast is the ratio ofthe brightest to darkestpixels in an image.

Photoshop – Project

Let’s do something – Roy Lichtenstein pop art.

Start with a photo image, convert it.


Here’s the photo.

Need to create a solid colour background, clipthis image, and insert it on the colour first.


Need to create a solid colour background

Clip this image, and insert it on the colour first.

Solid background (Select colour first)

To duplicate a layer, drag it to here.


We will cut out the image using the pen tool. This is an essential skill.

Photoshop's pen tool you have two options: Create a new work path and Create a new shape layer.

We will use the Create a new work path option

The pen tool has several different options for the resulting path. The most commonly used is "add to path area".


Using a blank canvas, Each time you click you create an anchor point.

We can add and delete anchor points on the path we have created. Right click on the pen tool on the toolbar to reveal further tools.


I used the Delete Anchor Point Tool to remove the forth anchor point.

Now, let's look at the Convert Point Tool for curvature modification and moving anchor points. With the convert point tool click and drag on the second anchor point. Without letting go, move the mouse around and see how it affects the curve. The line that is created is called the Tangent Line. The tangent line controls the curvature of the curve.


Click on one end of the tangent line and drag.

This breaks the tangent line in half and creates sharp path changes.


Cutting.

Open your image in Photoshop and using your pen tool trace around the outside. There are two ways to do this. You could click and drag on each anchor point to get the right curves but I find this process too slow. I prefer to click around the object (essentially cutting it out with straight lines) and then go back and adjust the curves/anchor points.

Zoom in (Ctrl +) and out (Ctrl - ) as you work.

Photoshop

Cutting.

Select consecutive points along the outline, using closer spacing where the Curvature is larger.

Photoshop

Cutting.

Make sure that the lastAnchor point is the sameAs the first.

Then the entire sequenceWill ‘close’ and be a single curve.

Photoshop

Select Edit->Define Custom Shape

Photoshop

Now the Custom Shape Tool shows our new shape.

Photoshop

Change the path into a selection (not as easy as you think – Control-return on a PC); then invert (so the background is foreground) and type delete. Control-D unselects:

Photoshop

Desaturate: (Ctrl + Shft + U) – we’re in the ‘dots’ layer.[Or Image->Adjustments->Desaturate]

Photoshop

Try Image->Adjustments->Threshold.

Photoshop

Play with Filter->Gaussian Blur. I used 3.3 pixels.

Photoshop

Right click on the ‘dots’ layer, select duplicate. Make a new layer and you’ll have 2 windows open in Photoshop.

Image->mode->greyscale (discard colour info)

Photoshop Image->mode->bitmap. (Flatten layers: ok) Select the halftone screen.

Photoshop The halftone parameters specify the dots you’ll see. Make them round.

Photoshop Here’s what the new layer looks like now.

Finally, we have toMove the dots backTo the ‘dots’ layer.

Photoshop

Now we need a new layer for the main image. Our copy has its own.

In the image that has just been edited, Select->all, then Edit->copy. Now click on the old ‘dots’ image and paste (edit->paste). This should create a new layer with the halftone image in it.

Move layers about, if you have to, until it looks like:

Photoshop

Now a weird bit.Create a Clipping Path between the new layer and the "dots" layer. Hold down the ALT key and move your cursor between the 2 layers in your Layers Palette. When the cursor turns into a "double bubble" (see image below) click to create the clipping path.

Photoshop

Link the top two layers (CLICK on them one at a time while holding SHIFT, then Layer->link layersThen merge them into one layer by typing CTL-e or using Layer->Merge layers. You might SAVE at this point.

No change will be seen in the images.

Duplicate the ‘dots’ layer (call it ‘white’ and place ‘white’ between the blue background and ‘dots’ (next from top)

Photoshop

Here’s whatit looks likenow.

Photoshop

Link the top two layers (CLICK on them one at a time while holding SHIFT, then Layer->link layersThen merge them into one layer by typing CTL-e or using Layer->Merge layers. You might SAVE at this point.

No change will be seen in the images.

Duplicate the ‘dots’ layer (call it ‘white’ and place ‘white’ between the blue background and ‘dots’ (next from top)

Use the paint can tool and brush tool to remove all black from the area.

Photoshop

Photoshop

Change the blend mode on ‘dots’ to Multiply.

Photoshop Select a colour for the lips

Rename layer as LIPS

Photoshop

Create a Clipping Path between the "lip" and "white“ so you don't colour over the lines.

Now for the colouring. Change the foreground colour to white. Get your Paint Brush Tool ( ) and start painting where you want to the colour to appear. Use a hard brush with the opacity set to 100%. Make sure that you zoom in when colouring, so that it is nice and tidy! tidy!

Personally, I set the LIPS image colour to white and thenpaint on one layer as I would a painting.

Photoshop

Here’s my result.

Photoshop

Here’s what the ‘lips’ layer looked like. It is hidden beneath dots, so the strokes don’t show up.

Photoshop

Some people make a career doing Photoshop work.

It is just a tool, one of many. I wanted to show what this could do and how it might be used. It is up to you whether you use it and for what.

Photoshop

Photoshop

Photoshop

LView

Small, quick, and useful. Basic version is free.

Especially handy for:- Resizing- File format changes (JPEG to GIF, for example)- Adding transparency to a GIF- colour and gamma shifts

LView

Gamma

This has also beenResized to 300x225

LView

Colour balance(now its Mars…)

LView

Transparency – A colour in a GIF image can be designatedAs transparent, and then anything that falls behind that colour in an overlayed image can be seen.

Here’s an image.

Let’s make white theTransparent colour.

LView

Use Retouch->Background Color

Select ‘Dropper’

LView

The cursor becomes an eyedropper. Click the mouse when the dropper is in the image colour you want to select (white)

Select ‘Dropper’

The SAVE the file.Not Save-As.This the file had to be a GIF in the first place.

The image won’t look any different.

LView

The SAVE the file.Not Save-As.This the file had to be a GIF in the first place.

The image won’t look any different.

Crystal I

OK, this one is my own.

I wrote it to add some features that I had not seen, but wanted.

-Colour editing (change a colour to another)- easy histogram editing- restoration- many contrast and edge enhancements.

It’s not a drawing program.

Crystal I

Opens with a small window, menus only.Images have their own windows.

Sadly, to do a colour image one must enhanceeach colour individually – red, green, blue. The system helps with that.

Crystal I

Here is a photo taken with no flash. Looks very dark.

Crystal I

Convert to grey (Still black). Then select Contrast -> histogram edit

Crystal I

Convert to grey (Still black). Then select Contrast -> histogram edit

The histogram Shown is the graphof the grey levels in the image.This one is lumpedto the low levels (dark).try shifting higher and stretching.

Crystal I

Note that the histogram now has a different nature, and that the image has detail in it.

Crystal I

It does some cool things in restoration (de-blurring) and editing, but is limited as an artistic tool. The coolest thing it does is motion blur reduction.

Original

RestoredImage

Documents

Images II