Archive for the ‘Howtos’ Category

Print sizes and resolutions for photographs

Monday, February 21st, 2011
One of the most frequent questions I get asked is what resolutions to use when printing out photos. Here are some suggestions that I usually provide as a guide.

First decide what size the photos are to be printed out and crop them based on the corresponding aspect ratio.There are a number of standard sizes that photo shops print in. I have tabulated below some of the traditional sizes together with their physical dimensions in millimetres and inches.

For each of the standard sizes, some shops print variants of the standard dimensions to cater to varying aspect ratios. For example, although traditional 4R has an aspect ratio of 3:2, some shops give the option of printing similarly sized prints at 4:3 aspect ratio.

The resolution of a photo is the number of pixels per inch (ppi). To work out the number of pixels a photo should have, multiply the physical dimension in inches by the desired image resolution.

For example, a 5R print is 5 x 7 inches. Multiply by 300 ppi and your image should, therefore, be 1,500 x 2,100 pixels.

For optimal quality, use an image resolution of 300 ppi. For printing on a personal printer, 150 ppi is usually good enough, although some studios accept resolutions down to 100 ppi. Since all my prints are 4R in size, all my images are at 300ppi. This way, they are optimal for 4R and still good enough if I want to print up to A4 size.

Note that studios usually crop a small margin of up to 3%  around the photo. The cropped margin could be bigger on one side compared to the other. This is usually unnoticeable for most photos. Unless the subject is really tightly framed, in which case part of the anatomy, say a ear or finger-tip could be cut off the edge.

However, if your photo has a decorative frame or border that you’d added using a photo-editor, it will turn out uneven. Choose a studio that can crop the photo evenly all round. I find it easier to show the studio a sketch to illustrate when explaining.

Likewise, when using your own printer, it pays to do a few test prints to determine the right settings for even borders.

Standard print sizes, aspect ratios and optimum/minimum image resolution for printing.
Print Size Size

(inches)

Size

(mm)

Aspect ratio Optimum Resolution

(300 ppi)

Minimum Resolution

(150 ppi)

3R 3.5 x 5 89 x 127 7:10 1050 x 1500 525 x 750
4R 4×6 102 x 152 2:3 1200 x 1800 600 x 900
5R 5×7 127 x 178 5:7 1500 x 2100 750 x 1050
6R 6×8 152 x 203 3:4 1800 x 2400 900 x 1200
8R 8 x 10 203 x 254 4:5 2400 x 3000 1200 x 1500
S8R 8 x 12 203 x 305 2:3 2400 x 3600 1200 x 1800
10R 10 x 12 254 x 305 5:6 3000 x 3600 1500 x 1800
S10R 10 x 15 254 x 381 2:3 3000 x 4500 1500 x 2250
11R 11 x 14 279 x 356 11:14 3300 x 4200 1650 x 2100
S11R 11 x 17 279 x 432 11:17 3300 x 5100 1650 x 2550
12R 12 x 15 305 x 381 4:5 3600 x 4500 1800 x 2250
S12R 12 x 18 305 x 465 2:3 3600 x 5400 1800 x 2700

Freehand selection in GIMP (Part 2 of 14)

Sunday, February 20th, 2011
Select irregularly shaped objects in photos using the Free Select Tool in GIMP.

In the Basic GIMP series, we used the rudimentary Rectangle and Ellipse Select tools to create simple selections in a photo.

What if we want to select an object in a photo that has an irregular outline? Check out the Free Select Tool.

As with the other selection tools in GIMP, the Free Select Tool can be found at the top of the Toolbox.

Little red Japanese postbox

The red traffic cones and receding pedestrian are a tad distracting behind the postbox.

Arty interpretation of a postbox in Japan

Toning down the background focuses the viewer's attention on the main subject.

In the photo I snapped in Nara – Japan on a cool evening last autumn, I made the red postbox stand out by removing colour from its distracting surroundings and tinted the surroundings with a light reddish shade.

This is usually done to bring put the emphasis on a main subject by toning down the background, especially if the background is brightly coloured or distracting.

It is also a popular technique to turn a mundane snapshot into something arty.

Download the Before photo and follow along.

GIMP's Toolbox

Activate the Free Select Tool at the top of the Toolbox

Using the Free Select Tool

In the Toolbox, activate the Free Select Tool. Click (and let go of the mouse button) anywhere on the edge of the postbox. Move the cursor to the next point on the edge of the postbox and click again.

GIMP joins the two mouse clicks with a straight line to indicate the edge of the selection you are making. An anchor point is also created at each end of the edge to indicate where the mouse was clicked.

Around the corners of the postbox, the edges are rounded. Zoom in (press “+” on the keyboard) to get a better view to make a more precise selection.

Where the curved edge begins, click but hold down the mouse button and drag the cursor along the curved edge. You can see selection boundary trace around the curved edge.

At the end of of the curved edge, release the mouse button. To continue selecting straight edges, simply click at the next point.

Repeat the above techniques around the edge of the postbox until you are back to the starting point. This completes the selection process.

Along the way, if you click at the wrong place or make a botched tracing around a curved edge, press the Backspace key on the keyboard. GIMP will remove the previous anchor point and line segment. Press the Backspace key once to remove each previous anchor point and segment.

Decolourizing and adding the tint

Once the postbox has been selected, press Ctrl-I to invert the selection. Drain the colour from the selected surroundings and tint it a pale red by using the Colors > Colorize command from the main menu.

In the Colorize dialog box, set Hue to zero and Saturation to 15 by dragging the corresponding sliders.

Size matters – resizing and reshaping a photo in GIMP (Intermediate series: Part 1 of 14)

Saturday, February 19th, 2011

Starting off the 14-part Intermediate Photo Editing series for GIMP this weekend, this warm-up tutorial looks at resizing and reshaping a photo.

Ambush

Pict 1: This gruesome troll was laying in ambush amidst a bamboo grove by the roadside in Kyoto as I walked past towards the train station.

With cameras offering more and more megapixels, we frequently need to reduce the size of photos for emailing to friends or sharing online – to reduce upload and download time. Sometimes, we need to change the aspect ratio (between the width and height of the photo) of the photo, perhaps to use it as part of a web page design.

Scaling a photo
Scale Image dialog box in GIMP

Pict 2: Change the Width and Height pixel settings to resize the photo.

To reduce the size of a photo in GIMP, use the Image > Scale Image command from the main menu. A “Scale Image” dialog box pops up.

Change the Width and Height fields to the desired dimensions. Make sure the unit of measure for the Width and Height is in pixels (the default).

The chain link between the two fields locks the aspect ratio of the photo. Hence, you only need to adjust the pixel dimension of either the Width or the Height field and GIMP will calculate the corresponding pixel dimension for the other field so that the aspect ratio is kept constant.

Caution: Clicking on the chain icon will change it into a broken chain. The width and height can then be changed independently without preserving the original aspect ratio. Doing this for photos will cause distortions – people, trees and things in the photo become either tall and thin, or short and squat.

Leave the interpolation method to the default setting of “Cubic”. There is no need to adjust to adjust the resolution fields.

Press the “Resize” button and the pixels in the photo will be resampled.

Caution: Scale Image can be used to increase the size of photos but avoid that because the up-sampling will reduce the quality of the photos and make it appear blurry.

Reshaping a photo

To change the aspect ratio of a photo without causing any distortions, use either of the two following methods.

Portrait version of Japanese troll

Pict 3: The photo was cropped to a portrait orientation to zoom into the Japanese troll.

Use the Crop tool in the Toolbox to select the area in the photo to be retained. Use the Tool Options below the Toolbox to help select the area better. Check the “Fixed” checkbox to set a specific aspect ratio, width, height or size. Even after dragging out the selection, you can move the selection boundary or resize/reshape it before pressing “Enter” key to execute the crop.

Now that the photo is of the right aspect ration, use “Image Scale” to resize it if necessary.

What if the photo is so tightly framed that you don’t want to crop the forehead or an ear of the subject out of the photo? You’ll have to add pixels to the sides to make the photo fatter, or to the top and/or bottom to make the photo taller.

Dialog box for Canvas Size command in GIMP

Pict 4: Click the Center button to centre add new pixels equally between opposite sides.

Use the Image > Canvas Size to do this. A “Set Image Canvas Size” dialog box pops up.

Type the desired dimensions in pixels in the Width and Height fields under Canvas Size. Click the chain icon joining the two fields to de-couple them so as to specify a canvas with a different aspect ratio from the original photo.

Set the “Resize layers” dropdown box to “All layers”. Press the “Center” button to centre the photo.

A fatter image

Pict 5: New pixels have been added to the sides of the photo.

When you press the Resize button, additional pixels will be added either to both sides or to the top/bottom of the photo. Unlike the Scale Image command, the original pixels remain untouched.

Use “Image Scale” to resize the photo if necessary.

Caution: If the Width or Height dimensions are reduced, the photo will be cropped instead.

Fine-tuning and trouble-shooting

A taller image

Pict 6: New pixels have been added to the top and bottom.

If the photo was the Background layer before activating the Canvas Size command, the new pixels will take on the colour of the Background Color swatch in the Toolbox.

So in order to specify the colour of the new pixels, click on the Background Color swatch to select the desired colour – BEFORE activating the Canvas Size command.

If the photo was not the Background layer, activate the Image > Flatten Image command from the main menu before the Canvas Size command as well.

Adding a coloured border/frame

Sometimes, even though the photo is of the desired aspect ratio, we may want to add a coloured margin around it, either a white border to make it look like a traditional photo print, or a coloured frame for decoration.

A coloured photo frame or border

Pict 7: A solid-coloured photo frame/border has been added.

In this case, use the Canvas Size, and in the “Set Image Canvas Size” dialog box, increase the Width or Height setting while leaving the chain icon connected. Click the Center button to center the photo and set “Resize layers” dropdown box to “All layers” as before.

You can look at the preview thumbnail in the dialog box to see how thick the margin is with respect to the photo before pressing the “Resize” button.

Intermediate GIMP Series on photo or image-editing

Friday, February 18th, 2011

I will commence the Intermediate GIMP Series this weekend. It will run every weekend on Saturday and Sunday. That way, readers have more time to try out the tutorials and play with their vacation photos outside of work.

Due to positive comments and feedback from readers and friends on the 14-part Basic GIMP series in January, I’ve decided to run a follow-up series on GIMP, this time at intermediate level.
GIMP's splash logo for v2.2

v2.2 logo by Bill Luhtala

There will be 14 parts and should take us through March to the beginning of April.

Don’t expect anything too complex as I’ll try to keep explanations simple for the layman. The topics are based on suggestions from readers and I’ve arranged them to be useful and applicable in daily life and work.

There’ll still be some fairly basic stuff but we’ll also look at some more powerful controls for adjusting images, such as Levels and Curves.

If you have any comments, feel free to email me at johntan@tech4tea.com or simply comment in the pertinent posting.

Apple app (Free): Send Chinese New Year greetings in SMS and email

Wednesday, January 26th, 2011
Choose from a long list of pre-canned Chinese New Year greetings and well-wishes and send them as an SMS or email.

As an alternative or complement to traditional paper Chinese New Year cards, many have been sending well-wishes on SMS on the morning of the actual day, and throughout the day as well. You know – those long wordy festive greetings in Chinese characters that advertise the sender’s fingertip dexterity in churning out those characters on a tiny handphone.

Send SMS/email CNY greetings in Chinese

Look for this icon in the Apps store or its publisher's name "YYH Creative" in English.

This 春节短信 (兔年特别版)free app for Apple devices provides a long list of pre-canned Chinese New Year greetings and well-wishes that you can send as an SMS or email. There’s no english name, do a search for free Chinese New Year apps and look for the icon. The name of its publisher “YYH Creative” is in English though.

The well-wishes are organised into different categories based on recipients (mother, father, teachers, lover, boss) or theme (humour, sincere, classic). Many are customised for the Rabbit year since this will be the Year of the Rabbit in the Chinese horoscope.

There is also a small section for the upcoming Valentine’s Day although I have never sent a pre-canned Valentine’s Day message before.

Apart from sending a selected greeting through SMS or email, it can also be copied onto the clipboard or stored in a shortlist folder. Sent greetings are archived for future reference.

Although this app might be convenient for those who find it too tiresome to type their own New Year well-wishes, I would suggest amending the pre-canned greetings to personalise them.

A little knowledge of Chinese is needed to use this app, since the menus and categories are all in Chinese.

A word of caution to those who know only a little Chinese but want to impress by sending a bombastic greeting in Chinese, get someone to toss a quick glance at the message. A casual browse under the category for greetings to teachers contained one addressing the recipient as a lover, although the rest of the message was indeed written with teachers as the recipient. A typo perhaps?

Overall, a useful app for those trying to minimise RSI on their fingers from pressing out those long Chinese New Year SMS in Chinese characters.

Apple app (Free): Dress up as the God of Wealth

Tuesday, January 25th, 2011

Bring a smile to friends and relatives this Chinese New Year by sending them a festive greeting dressed up as the traditional God of Wealth.

“A FREE single-trick app that does one thing, it ran pretty smoothly on my iPhone without hanging or major complains, and provided much amusement to my kids putting all manner of chimpanzee/orang utan faces onto the digital placard.”

The Lunar New Year is just round the corner. This year it falls on 3 Feb – that’s next Thursday.

Part of the Chinese New Year tradition is to send greeting cards carrying festive greetings. Many carry well wishes for good health, happiness, and success in career or studies.

The Chinese God of Wealth with your own face

Bring Chinese New Year greetings dressed up as the traditional God of Wealth.

By far, the favourite festive greeting is to for prosperity, such that “Gong Xi Fa Cai” has become a set phrase even in the English language. It means “Congratulations on hitting it rich!” And that usually happens when the Chinese God of Wealth (财神 – cai shen) pays you a visit.

Combine the two and you get an Apple app that allows you to make a simple greeting card on your iPhone, iPad or iPod Touch, dressed up as the ubiquitous god bearing a well-wishing banner and smiling favourably on the recipient.

Remember those cardboard placards of cartoon characters with the face cut-out so that you can scramble up behind the placard and stick your face through the hole and pose as the cartoon character? Well, “God of Wealth camera” simulates that.

Using the app

The app is simple and comprises four simple steps with a few options to choose from. You can jump to any step by pressing the four buttons at the bottom of the screen. Look here for screenshots.

Step 1: Take a photo with the camera on your Apple device or choose one from the photo album. A front facing portrait works best here.

Step 2: Identify the face. A translucent Cai Shen face is initially placed where the app thinks the face is. You can move the face, rotate it and resize it to superimpose it on the face in the photo ( if there is more than one face) that you want to use.

Step 3: The face is put in the hole in the placard. There are five designs available, and for each of these, you can change the default text greetings on the banner that Cai Shen holds in his hands. You can also choose to remove the long beard (actually it’s the moustache) from the face.

Step 4: Export the picture to your album as a jpeg file, or post it to your Facebook account from inside the app. All done in a few minutes.

Wish-list

Potentially, the most time-consuming step is the second step. If you’re lucky, the face is properly positioned when you first go into Step 3. Otherwise, you have to go back and forth between Steps 2 and 3 until you get it right: adjust face position, size and rotation in Step 2, see its result in Step 3 and go back to Step 2 to re-adjust.

Some might find it tiresome, but take it as a challenge or game of sorts and it can actually begin to become a little fun, especially when you finally position it right. If only you can adjust the face directly in Step 3, it would be more intuitive and less iterative.

It also gets difficult to activate the side and corner handles to adjust the size and rotation of the face when it is very small. If only you could zoom in to make the face bigger just for making adjustments. But then again this is a free app. So just snap or choose a photo where the face is large.

Why the option to to remove the moustache? I found that out soon enough. It makes it so much more tricky (fun?!) to position the face with the moustache in the right place! So if you don’t have the gumption, just turn off the “beard” option.

I tend to leave the greetings alone. Typing in English is no go, only the first four letters appear on the banner. You have to type in Chinese characters in typical four-worded wishes. Even then, I find the Chinese characters stiff and blocky. The default calligraphy based greeting on those banners look much nicer unless you have a compelling reason to change the greetings – like putting a funny or naughty greeting instead.

Overall, a pleasant app that doesn’t hang, does one thing pretty well, kills time and keeps the kids entertained.

Disclaimer: I am not associated with the developer in any way. Just thought I’ll post a digital-imaging related app for the festive season.

Some useful links for GIMP users

Sunday, January 16th, 2011

Here’s a short list of links for GIMP users. Feel free to contribute additional links you feel are relevant and useful.

GIMP's splash logo for v2.4

v2.4 Logo by Paul Davey

Forums and discussions boards that contains tutorials and answers questions about GIMP techniques and problems.

Series on using GIMP for photo-editing

Saturday, January 15th, 2011

We have come to the end of the Basic GIMP series. I’ve tried to cover the most basic and commonly needed tasks a photographer needs to correct or enhance his/her photos.

GIMP's splash logo for v2.6

v2.6 Logo by Alexia Death

For an exhaustive descriptive of every feature in GIMP, you may find the user manual useful.

Hopefully, you’ve enjoyed the articles as much as I’ve enjoyed writing them.

If you have any queries or comments on any of the techniques or steps described in the tutorials, please feel free to email me.

Intermediate series on GIMP in Feb 2011

Some readers and friends have encouraged me to continue with the series. As such, I will be commencing an intermediate series on using GIMP in February 2011. This will cover more complex photo correction and enhancement techniques.

If there are any photo-editing techniques or tasks that you want me to cover, email me at johntan@tech4tea.com.

Feel free to let me know if you want to contribute some of your own favourite techniques.

Use GIMP to create vignettes and digital photo frames (Final Part 14 of 14)

Friday, January 14th, 2011
Dog in a pram

Pict 1: This dog's eyes caught mine outside the Todaiji - a UNESCO World Heritage Site in Nara, Japan.

Create simple vignettes or digital photo frames for those special photos.

Yesterday, we used the rudimentary Rectangle Select Tool in GIMP to create a selection for making local adjustments to specific parts of a photo.

Today we check out the Ellipse Select Tool and use it to make simple vignettes and photo frames for digital photos.This is also the most common request that I receive from readers.

Ellipse Select Tool
Selecting the foreground colour in GIMP

Pict 2: The same colour picker is used whenever selecting colour in GIMP.

The Ellipse Select Tool works in the same way as the Rectangle Select Tool.

In Picture 1 above, I want to add an oval photo frame around the dog. This will exclude the clutter and distractions in the vicinity of the dog and put the focus on the dog itself. Download the photo of the dog and follow along.

Since the photoframe around the dog will be an upright oval, crop the original photo from a broad landscape orientation to a tall portrait orientation.

Cropped photo of dog with oval mat

Pict 3: Crop the original photo and add the inner mat of the "photo frame" to exclude the distracting surroundings.

Using the Ellipse Select Tool, drag the cursor around the dog to form a tight oval selection around it (I have no idea whether it’s male or female). Now all the pixels inside the oval selection boundary is selected.

To create the inner mat for the photoframe, we want to fill the area OUTSIDE the oval with dark brown. Click on the Select > Invert command from the main menu to invert the selection. You can also press Ctrl-I on the keyboard as a shortcut. The area outside the original selection is now selected, while the original selection is now omitted.

Click on the foreground colour swatch in the Toolbox and select a dark brown colour from the “Change Foreground Color” dialog box that pops up (see Picture 2 above).

Dog in a "photo frame"

Pict 4: The dog is now in a simple "photo frame" with inner matting.

To select a colour, first click in the thin vertical strip of colour to pick the colour family. The big square colour swatch shows the different tones of the selected colour family. Click within this big square to select the foreground colour.

From the main menu, select the Edit > Fill with FG command to fill the mat with dark brown (see Picture 3).

If you simply want a simple oval photoframe, you can stop here and crop the photo closer to the oval frame.

For a photoframe with an inner mat, you need to add the outer frame. Repeat the above steps but make a slightly bigger oval selection and fill it with orange (see Picture 4). Don’t forget to press Ctrl-I to invert the selection before filling it with orange.

Vignette Effect
Dog in a vignette

Pict 5: The dog is now nicely vignetted.

A vignette is a frame with blurred edges, usually oval in shape – although you can ceate a vignette of any shape you want.

Activate the Ellipse Select Tool from the Toolbox. For a rectangular vignette, use the Rectangle Select Tool instead.

In the tool options below the Toolbox, click the “Feather edges” checkbox . A Radius slider appears that determines the thickness of the blurred region at the edge of the selection. Set the Radius setting to the maximum of 100.

Drag an oval selection around the subject. Press Ctrl-I to invert the selection and fill it with white or any colour you want. A quick shortcut to set the Foreground colour to white is to press “D” followed by “X” on the keyboard.

Selecting specific portions of a photo for editing (Part 13 of 14)

Thursday, January 13th, 2011
Selecting certain areas in a photo allows only those specific areas to be targeted for editing. Any adjustments and tweaks applied will be limited to only the pixels within those selections.

Following my 6-part series in Digital Life (The Straits Times)  on basic photo-editing using GIMP, I received encouraging feedback and requests from readers and friends to cover more topics.

One of these was about the various ways of creating selections and vignettes in GIMP. A follow-up article was run on DL after the series. I cover these today and tomorrow for those who had missed it.

Selections for local adjustments

So far, most of the adjustments we’ve learnt have been applied to the entire photo. For example, removing a colour cast or darkening and overexposed snapshot. Such adjustments that are applied to the entire photo are known as “global adjustments”.

GIMP's selection tools and tool options

Pict 1: GIMP's selection tools are at the top of the Toolbox while the tool options are below.

What if we want to adjust only a small portion of a photo? For instance, we want to lighten only the face of a person standing in the shadows. Lightening the entire photo just to lighten up one face in the shadows could lead to the faces of other people standing in the sun to become overly bright instead.

In these cases, select only the areas in the photo that needs to be adjusted. While those areas are selected, any adjustments applied will be limited to the pixels within those selections. Such adjustments where edits are done only on a specific part of a photo are called “local adjustments”.

As a workflow, global adjustments to the whole photo should be largely completed before commencing on local adjustments on specific areas of the photo.

In GIMP, the tools for making selections are located right at the top of the Toolbox (see Picture 1 and the sidebar on “GIMP’s selection tool options”). Today we try out the most basic selection tool – the Rectangle Select Tool.

Rectangle Select Tool

With the Rectangle Select Tool, simply click in the photo and drag the cursor to form a rectangular selection.

You should see a moving black-and-white dashed line (resembling a single file of marching ants) marking the outline of the selection. The pixels inside the boundary are now selected and whatever adjustments applied will affect only the selected pixels.

Adjusting the selection boundary (and not the pixels inside)

After you have made the initial selection, you can resize the selection to select a bigger or smaller area.

Move the cursor near the sides or corners of the rectangular selection until the cursor turns into a white triangle. Drag the corner to resize the selection boundary.

Deer chewing on an iron chain

Pict 2: This demure deer was chewing on an iron chain for tea when I visited in Nara - Japan's ancient capital.

To move the entire selection boundary, move the cursor near the centre of the selection. When the cursor appears as two criss-crossing double-headed arrows, click and drag to move the selection boundary.

Once you have adjusted the selection boundary until it is where you want it to be and of the right size, you can edit the pixels within the selection.

Adjusting the selected pixels
Putting text captions on a photo

Pict 3: Captions on the photo is illegible unless its background is made lighter for more contrast against the dark text.

In Picture 2, I wanted to place a caption to label where the deer hails from. You can see that any text placed in the photo would be rather difficult to make out against the distracting background (see Picture 3).

Layers dialog in GIMP

Pict 4: The captions reside in its own layer above the photo. Select the background layer first before increasing the brightness.

You can use the Text Tool to add captions. Any captions added will reside on its own layer above the background layer containing the photo.

Using the Rectangle Select Tool, I made a rectangular selection around the captions. Making sure the background layer with the photo (and not the text layer containing the caption) is selected (see Picture 4), I activated the Colors > Brightness-Contrast command from the main menu.

In the Brightness-Contrast dialog box, I increased the brightness of its the selected area in the photo by dragging the Brightness slider

Iron chewing deer with captions

Pict 5: This iron chewing deer awaits you should you visit the Deer Park in Nara.

At about 100, the dark caption became more legible (see Picture 5).

In the final episode of this series tomorrow, we’ll use the Ellipse Select Tool to create simple digital photo frames, as well as vignettes with blurred edges.