Info on Scanning for Website

I need advice on scanning prints for my website. I've been told

that scans for the web should be low res, around 72 dpi or so. The

scans at that dpi look bad. Should I scan at a higher dpi? I have

PS 6, and am looking for the best methods to improve the looks of

the image after it is scanned. I would appreciate any advice.

 

Thanks,

Duane

Scan at 300 or 600 dpi if you have the hard disc space. Then, in your Photoshop software

convert it to 96 dpi or 100 dpi. I suggest you not use any software to manipulate the

image before you place it in Photoshop. Do all manipulations in Photoshop.

Timber,

Thanks for the information. What are your recommendations for tools to use once in PS? The scans aren't as vibrant as the original, and I need to get the color and contrast back up. I've experimented with curves, but I seem to make my image worse. Once again, thanks.

 

Duane

Here's an example. This one was scanned at about 150 dpi, and turned out better than some so far.

Take the conservative road firstly. Consider that your picture will be seen on 50 different

types of screens on the internet. If they view it on a new LCD screen, the colors may be

more 'vibrant'. Simply by tilting your screen, you change the contrast of the picture. You

have no control of how the viewer maintains their screen angles. You should view your

output on 2-3 screens as a test just using 'flat' settings. I think it is OK to diddily with

taking out bluishness in your blacks by cutting off the 'toe' of the graphical curve with

Photoshop. But I would be careful after this. If you have a analog screen, I don't think

you have the contrast of an LCD screen. If you play around with contrast, you will make

skin tones unnatural in color. BW is more artistically forgiving.

 

You might have your negatives scanned; and then use this as the output for your pictures.

The pictures in my portfolio were actually scanned directly from a wedding book, and

these were prints. I simply used a flat setting after looking at the output from 'curves' and

other playful settings.

 

A local pro lab here in San Francisco only charges $2 per negative for scans in 2 1/4. I

think you should start here rather than to spend much time trying to gain 'latitude' or a

longer tonal range in prints. What is your time worth?

 

Also, you should gain some sharpness from the negative scan. Remember that color

prints are printed with dichroic light which is 'mixed' in the chamber of the enlarger. This

reduces the sharpness of the final print. But with digital, the little pixtels are transferred

without loss of sharpness from one point to another unless there is some further technical

feature I do not know about.

 

You need to also know that the amount of color correction you can do is limited with

prints that are scanned. For example, you cannot really change a incandescent amber

color cast to a pure 'white light' level by scanning a print and using photoshop. You will

run out of balancing colors when you do. There are simply limits to what you can do to

reinterpret scans from prints.

 

Take the conservative approach, get the negatives scanned, and start over from there.

You will have lots to play with in making choices from a scanned negative.

Don't change the dpi after scanning. This is pointless and has nothing to do with screen display. Ignore numbers like 72 and 96.

 

Resize your images to the number of pixels you want on the screen. Screens display pixels. DPI is for printing.

 

Believe me, this is the way it is. Anything else you hear is nonsense.

I scanned in 300 dpi. We output in pixtels at 100 pix per inch. 100 is chosen because

it is mathematically close to 96. This 100 number makes it convenient for math purposes

to determine a screen size in inches of a picture approximately. Sure, we are off about 4

-5%, so what. Most modern screens of 2 years old or so are 96 pix per inch, and more. I

do not keep up with the most recent specs. However, I scanned at 300 dpi and did my

output at 100 pix rgb and it worked fine for me considering that I could not lay my prints

on the glass! They hovered above the glass mostly in my attempts to scan from a wedding

book! My examples are not of "high" quality due to several reasons I am not going to

detail here. However, I do like pastel skin tones. I tried to play with curves to make the

colors more vivid, and it consequently made skin tones plastic and contrasty looking.

 

If you say you scanned at 300 DPI and output at 100 DPI to the screen, I know what is

happening (pixtels) even though your technical words are missplaced, you communicate

with me.

CORRECTION: I did write DPI on output. I meant "pixtels". But to me a dot on a screen is

a dot and they come in dots per inch on the screen, and the proper word for this is

"pixtels".

IMO, it is a waste of time just scanning for a web site. Scan for the maximum resolution

(digital information) you can handle with your scanning and computer equipment. I scan

35mm @ 5400 dpi, 16 bit. Then resize it to print size @ 300 dpi (like 11X14 @ 300 dpi).

240 or 300 dpi is a fairly widespread resolution for ink-jet printers. I then save that image

for storage, (many people save the original high-rez scan without touching it as a sort of

digital negative).

 

Now you have a high resolution RGB file of that image for a lot of different uses. One that

starts out with the most info for manipulation in PhotoShop ... which is a far more

powerful program than any provided with a scanner.

 

For web use use PS to make your conversions. The first step of which is to use the high rez

file to convert to sRGB color-space ( go to PS menu > Image > Mode > Assign Profile >

and select sRGB from the list of profiles in the drop-down menu). You will see the image

now change somewhat, so use levels or curves and whatever else to re-correct it until it

looks good on screen again.

 

Now to resize it, determine the on screen size you want. Let's use the photo.net

requirements as an example (511 pixels per inch maximum on the width, and a file no

larger than 100K in total):

 

1) Go to PS Menu > Image > click on Image Size > and set 511 in the pixel width window.

As Jeff said, you do NOT need to set 72 in the resolution window, you can leave it as is @

300 pixels. Click OK.

 

2) The image will now downsize on your screen to a postage stamp size. To look at it

actual size go to > View > Actual Pixels and click/select it. The postage sized image will

now jump back up in viewing size so you can determine if further corrections need to be

made.

 

3) often the image will need a little more sharpening (sharpening should always be done at

viewing size after you resize)

 

4) Size for web: Go to > File > Save For Web and click/select it. A window will open with

your image on it. At the top are tabs. Click 4 UP and 4 versions of your image will appear.

At the bottom left will appear the file size with the first one being the original size, and

then each successive one in descending file size. Pick/select the one closest to 100K. To

the right are controls to refine the size. use the quality slider to adjust the file to be 100K

or smaller. Click OK and a save dialog box will open to let you place the web image in a

desk-top file.

 

When prompted to save or not save the original image be sure to select DON"T SAVE, so

the corrections you just made aren't applied to the original larger file.

What is a "pixtel"? Is it a new form of cell phone? Or is is a very small TV set?

 

Scanning at just 300 or 600 ppi is to choose a stupidly low resolution unless you are

planning on having either extremely small or extremely pixelated output Anyone who

has a quarter of a clue about what they are talking about would know this. But then

again they would also understand the difference between a pixel and a dot of ink on

paper. You should be scanning at the full visual resolution of the scanner being used.

 

Perhaps we can next look forward to TB's explanation of color spaces, creating

profiles and calibrating a monitor and a printer? Such a tract should be very

entertaining.

The advice you got about scanning at high resolution is spot-on. You have a file that you can do with as you will - make prints, web images, etc. Disk space - both hard drive and CD - is cheap. Don't shortchange yourself.

 

The worst option is usually scanning at a low resolution. Scanners typically have one or more 'native' resolutions. This is governed by the sensor pitch and stepping motor resolution. Scans made at these resolutions have each output pixel mapped to a single input pixel. A low resolution scan will look crappy and pixellated. To see the effect, open a high resolution, reasonable size image in Photoshop. Make a duplicate. Downsample one to a small dimension - say 600x400 pixels using Bicubic interpolation. Downsample the other using Nearest Neighbor. The NN version is what a low res. scan will look like.

 

Scanners (or the scanner driver) also usually interpolate from the scan resolution to the desired resolution, if the scanner is not capable of running at the resolution you specify. The interpolation algorithm used is rarely specified, and you can almost always do better in Photoshop.

 

Finally, as pointed out above, ignore the ppi settings. All a web browser cares about is the number of pixels. Fixed ppi for monitors only made sense when people were using Macs with integrated monitors whose resolution could not be changed. These days, the screen dpi depends on monitor size and resolution. For example, my primary desktop editing monitor, a 22" job, runs along at 129 ppi. The high-res laptop I am typing on is 124 ppi. My older laptop is 91, a second monitor here in the office is 112, etc., etc.

 

It's easier to think in terms of screen size. The lowest resolution people interested in viewing photos over the web are likely to use is 1024x768. A 500 or so pixel wide image (as Jeff points out this is what photo.net uses as well) will take up about half the screen width. Image resolution does not factor into the equation. (Actually not quite true - older versions of IE converted everything to 96(?) ppi for printing from web pages, but based this on the stated resolution of the web image. Some photographers intentionally stored their images at 1 or 2 ppi resolution so people trying to steal images from their web sites would get a print that spanned 26 pages.)

Thanks to everyone for their responses. So... I should scan at the highest resolution my flatbed will accommodate, which I believe is 1200 dpi. After I make my adjustments in PS, I should use the "save for web" function in PS and save as a jpeg. Correct?

Yes. But read my procedure by the numbers. If you leave out a step it won't work.