losing quality when resizing with ImageResizer

Question

I'm using the ImageResizer .net library. It works as expected, but one image messes around. I've uploaded the image below. I've already tried some things like format=jpg&quality=100, only width=220, also different sizes, but it always adds this blurry border around the image.

The original image is a png.

This one is the original image:

This one is resized by the ImageResizer:

And this one is resized with photoshop:

EDIT: If you're running into the same issue. Try to set up the SpeedOrQuality Plugin. I've set it to speed=3 and the image is sharp again.

Community · Accepted Answer · 2017-02-08 15:07:26Z

2

Vector graphics require different resampling algorithms than photographs.

ImageResizer V4 includes higher quality image resampling options under the FastScaling plugin.

For graphics (non-photographic images), I suggest playing with &f.sharpen=0..100, &down.preserve=-5..5, and &down.filter=Robidoux. Make sure &fastscale=true and FastScaling is installed.

You can certainly find a good configuration for your rasterized vector art and set up a preset for it. FastScaling is capable of much better resampling than Photoshop - on par with Lightroom, in fact.

Enabling fastscaling alone helps substantially (?width=200&fastscale=true):

Adding sharpening gives a very clear result: (?width=220&fastscale=true&f.sharpen=100):

Visibly crisper than Photoshop:

edited Feb 8, 2017 at 15:07

CommunityBot

11 silver badge

answered Dec 8, 2015 at 2:54

Lilith River

16.5k2 gold badges46 silver badges81 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Tristan Over a year ago

What is the equivalent syntax for the C# API? instructions["fastscale"]="true" ?

Benjamin Baumann · Accepted Answer · 2015-12-07 14:45:57Z

0

Each time you save a jpeg, you loose quality (the image is reencoded). I would recommend using the same quality as the original image was save against, it should give the best results.

Using a higher quality is not recommended as it will artificially try to improve quality, mistaking approximations done by previous encoding for details, resulting in things like the blurry border.

Aside that, usually, one should not use a quality over 95 for jpeg encoding.

answered Dec 7, 2015 at 14:45

Benjamin Baumann

4,0852 gold badges28 silver badges37 bronze badges

6 Comments

NinjaOnSafari Over a year ago

if I understand you right, when I add just width=220 it should be good? But as you see I used the big image and resized it via imageresizer and the result is bad, then I resized it with photoshop to the same size and you see the result.

Benjamin Baumann Over a year ago

I think imageresizer will use a default value for quality if you omit the parameter. Try using width=220&speed=0, as shown in imageresizing.net/docs/v4/plugins/speedorquality . jpeg compression algorithms are different in different software, so it's quite expected to have quality difference between photoshop resizing and the imageresizer one. You should search for encoding parameters in imageresizer.

Benjamin Baumann Over a year ago

Did you set up the speedorquality plugin?

Benjamin Baumann Over a year ago

Also try using a lesser value for quality, e.g. quality=70 or quality=60.

NinjaOnSafari Over a year ago

yeah I did. I think the problem is the low size, cause when i resize it to 1000 then it is sharp like the original

|

Collectives™ on Stack Overflow

losing quality when resizing with ImageResizer

2 Answers 2

1 Comment

6 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

6 Comments

Your Answer

Sign up or log in

Post as a guest

Related