Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Use minimal scale for jpeg drafts #2240

Merged
merged 2 commits into from
Nov 22, 2016
Merged

Use minimal scale for jpeg drafts #2240

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
8f6b7b2
use minimal scale for jpeg downscaling
homm Nov 22, 2016
55fca48
protect .draft() from second call
homm Nov 22, 2016
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
6 changes: 5 additions & 1 deletion PIL/JpegImagePlugin.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -341,6 +341,10 @@ def draft(self, mode, size):
if len(self.tile) != 1:
return

# Protect from second call
if self.decoderconfig:
return

d, e, o, a = self.tile[0]
scale = 0

Expand All @@ -349,7 +353,7 @@ def draft(self, mode, size):
a = mode, ""

if size:
scale = max(self.size[0] // size[0], self.size[1] // size[1])
scale = min(self.size[0] // size[0], self.size[1] // size[1])
for s in [8, 4, 2, 1]:
if scale >= s:
break
Expand Down
79 changes: 58 additions & 21 deletions Tests/test_image_draft.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -2,36 +2,73 @@

from PIL import Image

CODECS = dir(Image.core)
FILENAME = "Tests/images/hopper.jpg"
DATA = tostring(Image.open(FILENAME).resize((512, 512)), "JPEG")


def draft(mode, size):
im = fromstring(DATA)
im.draft(mode, size)
return im


class TestImageDraft(PillowTestCase):

def setUp(self):
if "jpeg_encoder" not in CODECS or "jpeg_decoder" not in CODECS:
codecs = dir(Image.core)
if "jpeg_encoder" not in codecs or "jpeg_decoder" not in codecs:
self.skipTest("jpeg support not available")

def draft_roundtrip(self, in_mode, in_size, req_mode, req_size):
im = Image.new(in_mode, in_size)
data = tostring(im, 'JPEG')
im = fromstring(data)
im.draft(req_mode, req_size)
return im

def test_size(self):
self.assertEqual(draft("RGB", (512, 512)).size, (512, 512))
self.assertEqual(draft("RGB", (256, 256)).size, (256, 256))
self.assertEqual(draft("RGB", (128, 128)).size, (128, 128))
self.assertEqual(draft("RGB", (64, 64)).size, (64, 64))
self.assertEqual(draft("RGB", (32, 32)).size, (64, 64))
for in_size, req_size, out_size in [
((435, 361), (2048, 2048), (435, 361)), # bigger
((435, 361), (435, 361), (435, 361)), # same
((128, 128), (64, 64), (64, 64)),
((128, 128), (32, 32), (32, 32)),
((128, 128), (16, 16), (16, 16)),

# large requested width
((435, 361), (218, 128), (435, 361)), # almost 2x
Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Does this mean that if we request a draft image of (218, 128), we're getting something larger than that?

((435, 361), (217, 128), (218, 181)), # more than 2x
((435, 361), (109, 64), (218, 181)), # almost 4x
((435, 361), (108, 64), (109, 91)), # more than 4x
((435, 361), (55, 32), (109, 91)), # almost 8x
((435, 361), (54, 32), (55, 46)), # more than 8x
((435, 361), (27, 16), (55, 46)), # more than 16x

# and vice versa
((435, 361), (128, 181), (435, 361)), # almost 2x
((435, 361), (128, 180), (218, 181)), # more than 2x
((435, 361), (64, 91), (218, 181)), # almost 4x
((435, 361), (64, 90), (109, 91)), # more than 4x
((435, 361), (32, 46), (109, 91)), # almost 8x
((435, 361), (32, 45), (55, 46)), # more than 8x
((435, 361), (16, 22), (55, 46)), # more than 16x
]:
im = self.draft_roundtrip('L', in_size, None, req_size)
im.load()
self.assertEqual(im.size, out_size)

def test_mode(self):
self.assertEqual(draft("1", (512, 512)).mode, "RGB")
self.assertEqual(draft("L", (512, 512)).mode, "L")
self.assertEqual(draft("RGB", (512, 512)).mode, "RGB")
self.assertEqual(draft("YCbCr", (512, 512)).mode, "YCbCr")
for in_mode, req_mode, out_mode in [
("RGB", "1", "RGB"),
("RGB", "L", "L"),
("RGB", "RGB", "RGB"),
("RGB", "YCbCr", "YCbCr"),
("L", "1", "L"),
("L", "L", "L"),
("L", "RGB", "L"),
("L", "YCbCr", "L"),
("CMYK", "1", "CMYK"),
("CMYK", "L", "CMYK"),
("CMYK", "RGB", "CMYK"),
("CMYK", "YCbCr", "CMYK"),
]:
im = self.draft_roundtrip(in_mode, (64, 64), req_mode, None)
im.load()
self.assertEqual(im.mode, out_mode)

def test_several_drafts(self):
im = self.draft_roundtrip('L', (128, 128), None, (64, 64))
im.draft(None, (64, 64))
im.load()

if __name__ == '__main__':
unittest.main()