Increasing resolution but keep size same

[Summayah5FC7]

I have to design some posters for digital billboards at 960px by 480px.

I chose InDesign and it is easy to lay things out.

The client wanted at a highest possible quality.

So i exported it at 600ppi. the client replied saying the size is 12,000 x 6,000 pixels.

How do i keep it at 960 by 480 px and keep it at the best possible quality?

[Eugene Tyson]

InDesign will export at 72 ppi to image formats. 

Open the image in Photoshop and resample the image to 600ppi.

The pixels will revert to the size 960x480

But why are you doing this at 600ppi?

[Summayah5FC7]

I'm doing it at 600ppi because (in my mind) it's just a higher resolution and the filesize is not as large.

[James Gifford—NitroPress]

If this thread hasn't made it clear, pixels are pixels. An image is X pixels wide by Y pixels high; the notion of PPI is all but a phantom value. You can set the same image to 72 or 100 or 600 or 1200 ppi and it will be exactly the same image, and most applications (including digital billboards) will handle it exactly the same way... by its fixed pixel dimensions.

Just about the only time PPI/DPI really makes any difference is when translating a digital image to print, in which case you want X pixels per printed inch (usually 300) to get an optimum resolution. A few digital apps use PPI for scaling over and above how the layout or default handles it, but not many.

The PPI setting of your 960x480 pixel image is almost wholly irrelevant UNLESS the digital display tech demands an arbitrary PPI setting for some reason.

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[Alexandre Becquet]

Hello, it's not really for indesign but it could ;).

Ok, the goal is to show an image on a digital billboard and your client want he highest quality but does i known the specifications?

960px by 480px isn't a great size! if i do a quick convertion in cm, we are at 9,6cm by 4,8cm! And you can do what you want if the recommandation is 960px by 480px it's useless to do what you did.

Check this link about resolution 😉 it's in french but with the translation i think you'll understand 😉

Can you show us the effective PPI in Indesign?

[Summayah5FC7]

So do you recommend i do this in Illustrator?

The previous digital billboard job i did was in illustrator. I thought i'd do this job in InDesign as it would save me alot of time.

could you send me the link you mentioned?

Thank you

[rob day]

If the required pixel dimensions are 960 x 480, it doesn’t matter which application you use, the image quality is going to be limited by the pixel dimension requirement.

[rob day]

Hi @Summayah5FC7 , If you create an InDesign document sized to 960 x 480 px and set your Rulers to Inch units you will see that its dimensions in Inches is 13.333" x 6.6667":

If you then export the document to a JPEG image its pixel dimensions will be the dimensions in inches multiplied by the Pixel Per Inch (PPI) Resolution you choose in the Export dialog. So in the case above the exported pixel width would be 13.333 x 600 = 8000.

Or, if you setup a document to be 20" x 10", the Exported pixel width at 600PPI would be 12000 pixels. Sounds like your document is setup as 20" x 10"?

[Summayah5FC7]

My document is setup as 960 by 480 pixels. See below in pixels and inches.

[Summayah5FC7]

But when i export this as a png at 300 ppi. The image dimensions become 4000 by 2000. Please see below.

 

 

  

[Summayah5FC7]

They want the dimensions at 960 by 480. 

[Summayah5FC7]

I can see that if a export it at 72 PPI. The dimensions are 960 by 480.

But my question is that is the quality of the image affected?

 

[Summayah5FC7]

I can see a loss in quality. the image exported at 72 ppi is not as sharp as the image exported at 600ppi.

[Peter Spier]

For any given image there is an inverse relationship between the resolution (PPI) and output dimensions. Changing one will change the other in the same ratio, but will not affect the actual pixels in the image itself. You can see this if you open an image in Photoshop and go to the Image Size dialog and uncheck Resample, then make any change to either resolution or dimension.

Your 600 ppi export APPEARS sharper only because more pixels are being crammed into a smaller space on output. The image itself is the same and if you output at the same dimension as your 72 ppi export you will see they are identical.

[Peter Spier]

Further, when you say "Digital Billboard" I presume you mean a physical roadway sign meant to be viewed at a long distance. The farther the viewing distance the large the "spots" or pixels need to be physically in order to be seen individually to ascertain any details. It is impossible to resolve the detail in a 600 ppi image at 100 feet, let alone at several thousand. Hang a print from your desktop printer on the wall and view it from across the room as opposed to at arms length. Do you see the same details? Can you read the print? Could you do the same from the end of a hallway or across a street?

In this context of digital billboard, the resolution is irrelevant as long as the pixel dimensions are correct. The challenge is to keep your design elements large enough to actually be viewable.

[Brad @ Roaring Mouse]

"I can see a loss in quality. the image exported at 72 ppi is not as sharp as the image exported at 600ppi."

Resolution is irrelevant in your situation. Your billboard company wants a fixed pixel size, so you MUST export it at at 72dpi (Screen Resoutlion) to attain those pixel dimesnions. The image quality you get is the best you will achieve for those pixel dimensions.

The human eye is really good at making crap look good. At the size of a digital billboard, what you perceive as poor resolution will not show.

That being said there are ways to improve the look of your text. One is, you can export your file WITHOUT anti-aliasing. This keeps smaller text crisper, but may look more jagged as you will not benefit from the smoothing effect that anti-aliasing adds.

[rob day]

But when i export this as a png at 300 ppi. The image dimensions become 4000 by 2000.

That would be the expected output pixel dimensions because 13.333 x 300 = 3999.9. If you set the Resolution (PPI) to 72 you will get 960— 13.333 x 72 = 959.976.

Again the quality is limited by your client’s required pixel dimensions and the screen it is displayed on—if you want to resolve more details in the exported image, your client has to be willing to take a higher pixel dimension.

If this is for a web page you also have to consider that HTML pages are no longer static, it would be unusual for a 960 x 480 pixel image to display at that exact dimension in an HTML page. Any well made modern site is going to be responsive—the image will respond to the device and be resized up or down to fit the screen size.

[Summayah5FC7]

Thank you everyone for your replies.

I'm still new to this so i'll need some time to understand this fully.

below is the billboard. image that was sent was at 72 PPI

[Peter Spier]

It looks good.

I like to demonstrate the relationship between image size and resolution by using a balloon. Draw a checkerboard pattern on the balloon, then inflate it.

The checkerboard represents one pixel per square and the number of ixels never changes in the image no matter how much you inflate the balloon, but the pixels themselves get larger as the balloon grows, and the resolution, the number of pixels per inch of inflated image size, goes down.

[Eugene Tyson]

Why wasn't it just a vector file - resolution wouldn't have come into play at all.

[Peter Spier]

I suspect the technology requires pixels.

[Summayah5FC7]

I decided to use indesign this time instead of illustrator

[Eugene Tyson]

InDesign can work effortlessly with vector data - in both creation - and also in placing.

The right tool for the job, comes to mind.

[James Gifford—NitroPress]

The end use is on a rather low-res raster/pixel device. While any initial design format can be used, and there are any number of tricks to get better effective resolution (anti-alias, blurring, downsampling), the medium dictates the final limitations here.

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